Update To 11.40.268.0
[platform/framework/web/crosswalk.git] / src / sync / sessions / nudge_tracker_unittest.cc
index c76f3ec..c6a9dfb 100644 (file)
@@ -2,8 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "sync/internal_api/public/base/model_type_test_util.h"
 #include "sync/sessions/nudge_tracker.h"
+#include "sync/test/mock_invalidation.h"
+#include "sync/test/mock_invalidation_tracker.h"
+#include "sync/test/trackable_mock_invalidation.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace syncer {
@@ -59,6 +64,16 @@ class NudgeTrackerTest : public ::testing::Test {
     nudge_tracker_.RecordSuccessfulSyncCycle();
   }
 
+  scoped_ptr<InvalidationInterface> BuildInvalidation(
+      int64 version,
+      const std::string& payload) {
+    return MockInvalidation::Build(version, payload);
+  }
+
+  static scoped_ptr<InvalidationInterface> BuildUnknownVersionInvalidation() {
+    return MockInvalidation::BuildUnknownVersion();
+  }
+
  protected:
   NudgeTracker nudge_tracker_;
 };
@@ -70,55 +85,83 @@ TEST_F(NudgeTrackerTest, EmptyNudgeTracker) {
   EXPECT_FALSE(nudge_tracker_.IsSyncRequired());
   EXPECT_FALSE(nudge_tracker_.IsGetUpdatesRequired());
   EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::UNKNOWN,
-            nudge_tracker_.updates_source());
+            nudge_tracker_.GetLegacySource());
 
   sync_pb::GetUpdateTriggers gu_trigger;
   nudge_tracker_.FillProtoMessage(BOOKMARKS, &gu_trigger);
 
   EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::UNKNOWN,
-            nudge_tracker_.updates_source());
+            nudge_tracker_.GetLegacySource());
 }
 
 // Verify that nudges override each other based on a priority order.
-// LOCAL < DATATYPE_REFRESH < NOTIFICATION
+// RETRY < LOCAL < DATATYPE_REFRESH < NOTIFICATION
 TEST_F(NudgeTrackerTest, SourcePriorities) {
+  // Start with a retry request.
+  const base::TimeTicks t0 = base::TimeTicks::FromInternalValue(1234);
+  const base::TimeTicks t1 = t0 + base::TimeDelta::FromSeconds(10);
+  nudge_tracker_.SetNextRetryTime(t0);
+  nudge_tracker_.SetSyncCycleStartTime(t1);
+  EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::RETRY,
+            nudge_tracker_.GetLegacySource());
+
   // Track a local nudge.
   nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS));
   EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::LOCAL,
-            nudge_tracker_.updates_source());
+            nudge_tracker_.GetLegacySource());
 
   // A refresh request will override it.
   nudge_tracker_.RecordLocalRefreshRequest(ModelTypeSet(TYPED_URLS));
   EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::DATATYPE_REFRESH,
-            nudge_tracker_.updates_source());
+            nudge_tracker_.GetLegacySource());
 
   // Another local nudge will not be enough to change it.
   nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS));
   EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::DATATYPE_REFRESH,
-            nudge_tracker_.updates_source());
+            nudge_tracker_.GetLegacySource());
 
   // An invalidation will override the refresh request source.
-  ObjectIdInvalidationMap invalidation_map =
-      BuildInvalidationMap(PREFERENCES, 1, "hint");
-  nudge_tracker_.RecordRemoteInvalidation(invalidation_map);
+  nudge_tracker_.RecordRemoteInvalidation(PREFERENCES,
+                                          BuildInvalidation(1, "hint"));
   EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::NOTIFICATION,
-            nudge_tracker_.updates_source());
+            nudge_tracker_.GetLegacySource());
 
   // Neither local nudges nor refresh requests will override it.
   nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS));
   EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::NOTIFICATION,
-            nudge_tracker_.updates_source());
+            nudge_tracker_.GetLegacySource());
   nudge_tracker_.RecordLocalRefreshRequest(ModelTypeSet(TYPED_URLS));
   EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::NOTIFICATION,
-            nudge_tracker_.updates_source());
+            nudge_tracker_.GetLegacySource());
+}
+
+TEST_F(NudgeTrackerTest, SourcePriority_InitialSyncRequest) {
+  nudge_tracker_.RecordInitialSyncRequired(BOOKMARKS);
+
+  // For lack of a better source, we describe an initial sync request as having
+  // source DATATYPE_REFRESH.
+  EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::DATATYPE_REFRESH,
+            nudge_tracker_.GetLegacySource());
+
+  // This should never happen in practice.  But, if it did, we'd want the
+  // initial sync required to keep the source set to DATATYPE_REFRESH.
+  nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS));
+  EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::DATATYPE_REFRESH,
+            nudge_tracker_.GetLegacySource());
+
+  // It should be safe to let NOTIFICATIONs override it.
+  nudge_tracker_.RecordRemoteInvalidation(BOOKMARKS,
+                                          BuildInvalidation(1, "hint"));
+  EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::NOTIFICATION,
+            nudge_tracker_.GetLegacySource());
 }
 
+// Verifies the management of invalidation hints and GU trigger fields.
 TEST_F(NudgeTrackerTest, HintCoalescing) {
   // Easy case: record one hint.
   {
-    ObjectIdInvalidationMap invalidation_map =
-        BuildInvalidationMap(BOOKMARKS, 1, "bm_hint_1");
-    nudge_tracker_.RecordRemoteInvalidation(invalidation_map);
+    nudge_tracker_.RecordRemoteInvalidation(BOOKMARKS,
+                                            BuildInvalidation(1, "bm_hint_1"));
 
     sync_pb::GetUpdateTriggers gu_trigger;
     nudge_tracker_.FillProtoMessage(BOOKMARKS, &gu_trigger);
@@ -129,9 +172,8 @@ TEST_F(NudgeTrackerTest, HintCoalescing) {
 
   // Record a second hint for the same type.
   {
-    ObjectIdInvalidationMap invalidation_map =
-        BuildInvalidationMap(BOOKMARKS, 2, "bm_hint_2");
-    nudge_tracker_.RecordRemoteInvalidation(invalidation_map);
+    nudge_tracker_.RecordRemoteInvalidation(BOOKMARKS,
+                                            BuildInvalidation(2, "bm_hint_2"));
 
     sync_pb::GetUpdateTriggers gu_trigger;
     nudge_tracker_.FillProtoMessage(BOOKMARKS, &gu_trigger);
@@ -145,9 +187,8 @@ TEST_F(NudgeTrackerTest, HintCoalescing) {
 
   // Record a hint for a different type.
   {
-    ObjectIdInvalidationMap invalidation_map =
-        BuildInvalidationMap(PASSWORDS, 1, "pw_hint_1");
-    nudge_tracker_.RecordRemoteInvalidation(invalidation_map);
+    nudge_tracker_.RecordRemoteInvalidation(PASSWORDS,
+                                            BuildInvalidation(1, "pw_hint_1"));
 
     // Re-verify the bookmarks to make sure they're unaffected.
     sync_pb::GetUpdateTriggers bm_gu_trigger;
@@ -167,12 +208,11 @@ TEST_F(NudgeTrackerTest, HintCoalescing) {
   }
 }
 
-TEST_F(NudgeTrackerTest, DropHintsLocally) {
-  ObjectIdInvalidationMap invalidation_map =
-      BuildInvalidationMap(BOOKMARKS, 1, "hint");
-
+// Test the dropping of invalidation hints.  Receives invalidations one by one.
+TEST_F(NudgeTrackerTest, DropHintsLocally_OneAtATime) {
   for (size_t i = 0; i < GetHintBufferSize(); ++i) {
-    nudge_tracker_.RecordRemoteInvalidation(invalidation_map);
+    nudge_tracker_.RecordRemoteInvalidation(BOOKMARKS,
+                                            BuildInvalidation(i, "hint"));
   }
   {
     sync_pb::GetUpdateTriggers gu_trigger;
@@ -183,16 +223,15 @@ TEST_F(NudgeTrackerTest, DropHintsLocally) {
   }
 
   // Force an overflow.
-  ObjectIdInvalidationMap invalidation_map2 =
-      BuildInvalidationMap(BOOKMARKS, 1000, "new_hint");
-  nudge_tracker_.RecordRemoteInvalidation(invalidation_map2);
+  nudge_tracker_.RecordRemoteInvalidation(BOOKMARKS,
+                                          BuildInvalidation(1000, "new_hint"));
 
   {
     sync_pb::GetUpdateTriggers gu_trigger;
     nudge_tracker_.FillProtoMessage(BOOKMARKS, &gu_trigger);
-    EXPECT_EQ(GetHintBufferSize(),
-              static_cast<size_t>(gu_trigger.notification_hint_size()));
     EXPECT_TRUE(gu_trigger.client_dropped_hints());
+    ASSERT_EQ(GetHintBufferSize(),
+              static_cast<size_t>(gu_trigger.notification_hint_size()));
 
     // Verify the newest hint was not dropped and is the last in the list.
     EXPECT_EQ("new_hint", gu_trigger.notification_hint(GetHintBufferSize()-1));
@@ -202,8 +241,58 @@ TEST_F(NudgeTrackerTest, DropHintsLocally) {
   }
 }
 
-// TODO(rlarocque): Add trickles support.  See crbug.com/223437.
-// TEST_F(NudgeTrackerTest, DropHintsAtServer);
+// Tests the receipt of 'unknown version' invalidations.
+TEST_F(NudgeTrackerTest, DropHintsAtServer_Alone) {
+  // Record the unknown version invalidation.
+  nudge_tracker_.RecordRemoteInvalidation(BOOKMARKS,
+                                          BuildUnknownVersionInvalidation());
+  {
+    sync_pb::GetUpdateTriggers gu_trigger;
+    nudge_tracker_.FillProtoMessage(BOOKMARKS, &gu_trigger);
+    EXPECT_TRUE(gu_trigger.server_dropped_hints());
+    EXPECT_FALSE(gu_trigger.client_dropped_hints());
+    ASSERT_EQ(0, gu_trigger.notification_hint_size());
+  }
+
+  // Clear status then verify.
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+  {
+    sync_pb::GetUpdateTriggers gu_trigger;
+    nudge_tracker_.FillProtoMessage(BOOKMARKS, &gu_trigger);
+    EXPECT_FALSE(gu_trigger.client_dropped_hints());
+    EXPECT_FALSE(gu_trigger.server_dropped_hints());
+    ASSERT_EQ(0, gu_trigger.notification_hint_size());
+  }
+}
+
+// Tests the receipt of 'unknown version' invalidations.  This test also
+// includes a known version invalidation to mix things up a bit.
+TEST_F(NudgeTrackerTest, DropHintsAtServer_WithOtherInvalidations) {
+  // Record the two invalidations, one with unknown version, the other known.
+  nudge_tracker_.RecordRemoteInvalidation(BOOKMARKS,
+                                          BuildUnknownVersionInvalidation());
+  nudge_tracker_.RecordRemoteInvalidation(BOOKMARKS,
+                                          BuildInvalidation(10, "hint"));
+
+  {
+    sync_pb::GetUpdateTriggers gu_trigger;
+    nudge_tracker_.FillProtoMessage(BOOKMARKS, &gu_trigger);
+    EXPECT_TRUE(gu_trigger.server_dropped_hints());
+    EXPECT_FALSE(gu_trigger.client_dropped_hints());
+    ASSERT_EQ(1, gu_trigger.notification_hint_size());
+    EXPECT_EQ("hint", gu_trigger.notification_hint(0));
+  }
+
+  // Clear status then verify.
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+  {
+    sync_pb::GetUpdateTriggers gu_trigger;
+    nudge_tracker_.FillProtoMessage(BOOKMARKS, &gu_trigger);
+    EXPECT_FALSE(gu_trigger.client_dropped_hints());
+    EXPECT_FALSE(gu_trigger.server_dropped_hints());
+    ASSERT_EQ(0, gu_trigger.notification_hint_size());
+  }
+}
 
 // Checks the behaviour of the invalidations-out-of-sync flag.
 TEST_F(NudgeTrackerTest, EnableDisableInvalidations) {
@@ -274,6 +363,12 @@ TEST_F(NudgeTrackerTest, WriteRefreshRequestedTypesToProto) {
 TEST_F(NudgeTrackerTest, IsSyncRequired) {
   EXPECT_FALSE(nudge_tracker_.IsSyncRequired());
 
+  // Initial sync request.
+  nudge_tracker_.RecordInitialSyncRequired(BOOKMARKS);
+  EXPECT_TRUE(nudge_tracker_.IsSyncRequired());
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+  EXPECT_FALSE(nudge_tracker_.IsSyncRequired());
+
   // Local changes.
   nudge_tracker_.RecordLocalChange(ModelTypeSet(SESSIONS));
   EXPECT_TRUE(nudge_tracker_.IsSyncRequired());
@@ -287,9 +382,8 @@ TEST_F(NudgeTrackerTest, IsSyncRequired) {
   EXPECT_FALSE(nudge_tracker_.IsSyncRequired());
 
   // Invalidations.
-  ObjectIdInvalidationMap invalidation_map =
-      BuildInvalidationMap(PREFERENCES, 1, "hint");
-  nudge_tracker_.RecordRemoteInvalidation(invalidation_map);
+  nudge_tracker_.RecordRemoteInvalidation(PREFERENCES,
+                                          BuildInvalidation(1, "hint"));
   EXPECT_TRUE(nudge_tracker_.IsSyncRequired());
   nudge_tracker_.RecordSuccessfulSyncCycle();
   EXPECT_FALSE(nudge_tracker_.IsSyncRequired());
@@ -299,6 +393,12 @@ TEST_F(NudgeTrackerTest, IsSyncRequired) {
 TEST_F(NudgeTrackerTest, IsGetUpdatesRequired) {
   EXPECT_FALSE(nudge_tracker_.IsGetUpdatesRequired());
 
+  // Initial sync request.
+  nudge_tracker_.RecordInitialSyncRequired(BOOKMARKS);
+  EXPECT_TRUE(nudge_tracker_.IsGetUpdatesRequired());
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+  EXPECT_FALSE(nudge_tracker_.IsGetUpdatesRequired());
+
   // Local changes.
   nudge_tracker_.RecordLocalChange(ModelTypeSet(SESSIONS));
   EXPECT_FALSE(nudge_tracker_.IsGetUpdatesRequired());
@@ -312,9 +412,8 @@ TEST_F(NudgeTrackerTest, IsGetUpdatesRequired) {
   EXPECT_FALSE(nudge_tracker_.IsGetUpdatesRequired());
 
   // Invalidations.
-  ObjectIdInvalidationMap invalidation_map =
-      BuildInvalidationMap(PREFERENCES, 1, "hint");
-  nudge_tracker_.RecordRemoteInvalidation(invalidation_map);
+  nudge_tracker_.RecordRemoteInvalidation(PREFERENCES,
+                                          BuildInvalidation(1, "hint"));
   EXPECT_TRUE(nudge_tracker_.IsGetUpdatesRequired());
   nudge_tracker_.RecordSuccessfulSyncCycle();
   EXPECT_FALSE(nudge_tracker_.IsGetUpdatesRequired());
@@ -461,5 +560,409 @@ TEST_F(NudgeTrackerTest, OverlappingThrottleIntervals) {
   EXPECT_TRUE(nudge_tracker_.GetThrottledTypes().Empty());
 }
 
+TEST_F(NudgeTrackerTest, Retry) {
+  const base::TimeTicks t0 = base::TimeTicks::FromInternalValue(12345);
+  const base::TimeTicks t3 = t0 + base::TimeDelta::FromSeconds(3);
+  const base::TimeTicks t4 = t0 + base::TimeDelta::FromSeconds(4);
+
+  // Set retry for t3.
+  nudge_tracker_.SetNextRetryTime(t3);
+
+  // Not due yet at t0.
+  nudge_tracker_.SetSyncCycleStartTime(t0);
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+  EXPECT_FALSE(nudge_tracker_.IsGetUpdatesRequired());
+
+  // Successful sync cycle at t0 changes nothing.
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+  EXPECT_FALSE(nudge_tracker_.IsGetUpdatesRequired());
+
+  // At t4, the retry becomes due.
+  nudge_tracker_.SetSyncCycleStartTime(t4);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+  EXPECT_TRUE(nudge_tracker_.IsGetUpdatesRequired());
+
+  // A sync cycle unsets the flag.
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+
+  // It's still unset at the start of the next sync cycle.
+  nudge_tracker_.SetSyncCycleStartTime(t4);
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+}
+
+// Test a mid-cycle update when IsRetryRequired() was true before the cycle
+// began.
+TEST_F(NudgeTrackerTest, IsRetryRequired_MidCycleUpdate1) {
+  const base::TimeTicks t0 = base::TimeTicks::FromInternalValue(12345);
+  const base::TimeTicks t1 = t0 + base::TimeDelta::FromSeconds(1);
+  const base::TimeTicks t2 = t0 + base::TimeDelta::FromSeconds(2);
+  const base::TimeTicks t5 = t0 + base::TimeDelta::FromSeconds(5);
+  const base::TimeTicks t6 = t0 + base::TimeDelta::FromSeconds(6);
+
+  nudge_tracker_.SetNextRetryTime(t0);
+  nudge_tracker_.SetSyncCycleStartTime(t1);
+
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+
+  // Pretend that we were updated mid-cycle.  SetSyncCycleStartTime is
+  // called only at the start of the sync cycle, so don't call it here.
+  // The update should have no effect on IsRetryRequired().
+  nudge_tracker_.SetNextRetryTime(t5);
+
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+
+  // Verify that the successful sync cycle clears the flag.
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+
+  // Verify expecations around the new retry time.
+  nudge_tracker_.SetSyncCycleStartTime(t2);
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+
+  nudge_tracker_.SetSyncCycleStartTime(t6);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+}
+
+// Test a mid-cycle update when IsRetryRequired() was false before the cycle
+// began.
+TEST_F(NudgeTrackerTest, IsRetryRequired_MidCycleUpdate2) {
+  const base::TimeTicks t0 = base::TimeTicks::FromInternalValue(12345);
+  const base::TimeTicks t1 = t0 + base::TimeDelta::FromSeconds(1);
+  const base::TimeTicks t3 = t0 + base::TimeDelta::FromSeconds(3);
+  const base::TimeTicks t5 = t0 + base::TimeDelta::FromSeconds(5);
+  const base::TimeTicks t6 = t0 + base::TimeDelta::FromSeconds(6);
+
+  // Schedule a future retry, and a nudge unrelated to it.
+  nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS));
+  nudge_tracker_.SetNextRetryTime(t1);
+  nudge_tracker_.SetSyncCycleStartTime(t0);
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+
+  // Pretend this happened in mid-cycle.  This should have no effect on
+  // IsRetryRequired().
+  nudge_tracker_.SetNextRetryTime(t5);
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+
+  // The cycle succeeded.
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+
+  // The time t3 is greater than the GU retry time scheduled at the beginning of
+  // the test, but later than the retry time that overwrote it during the
+  // pretend 'sync cycle'.
+  nudge_tracker_.SetSyncCycleStartTime(t3);
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+
+  // Finally, the retry established during the sync cycle becomes due.
+  nudge_tracker_.SetSyncCycleStartTime(t6);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+}
+
+// Simulate the case where a sync cycle fails.
+TEST_F(NudgeTrackerTest, IsRetryRequired_FailedCycle) {
+  const base::TimeTicks t0 = base::TimeTicks::FromInternalValue(12345);
+  const base::TimeTicks t1 = t0 + base::TimeDelta::FromSeconds(1);
+  const base::TimeTicks t2 = t0 + base::TimeDelta::FromSeconds(2);
+
+  nudge_tracker_.SetNextRetryTime(t0);
+  nudge_tracker_.SetSyncCycleStartTime(t1);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+
+  // The nudge tracker receives no notifications for a failed sync cycle.
+  // Pretend one happened here.
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+
+  // Think of this as the retry cycle.
+  nudge_tracker_.SetSyncCycleStartTime(t2);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+
+  // The second cycle is a success.
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+}
+
+// Simulate a partially failed sync cycle.  The callback to update the GU retry
+// was invoked, but the sync cycle did not complete successfully.
+TEST_F(NudgeTrackerTest, IsRetryRequired_FailedCycleIncludesUpdate) {
+  const base::TimeTicks t0 = base::TimeTicks::FromInternalValue(12345);
+  const base::TimeTicks t1 = t0 + base::TimeDelta::FromSeconds(1);
+  const base::TimeTicks t3 = t0 + base::TimeDelta::FromSeconds(3);
+  const base::TimeTicks t4 = t0 + base::TimeDelta::FromSeconds(4);
+  const base::TimeTicks t5 = t0 + base::TimeDelta::FromSeconds(5);
+  const base::TimeTicks t6 = t0 + base::TimeDelta::FromSeconds(6);
+
+  nudge_tracker_.SetNextRetryTime(t0);
+  nudge_tracker_.SetSyncCycleStartTime(t1);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+
+  // The cycle is in progress.  A new GU Retry time is received.
+  // The flag is not because this cycle is still in progress.
+  nudge_tracker_.SetNextRetryTime(t5);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+
+  // The nudge tracker receives no notifications for a failed sync cycle.
+  // Pretend the cycle failed here.
+
+  // The next sync cycle starts.  The new GU time has not taken effect by this
+  // time, but the NudgeTracker hasn't forgotten that we have not yet serviced
+  // the retry from the previous cycle.
+  nudge_tracker_.SetSyncCycleStartTime(t3);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+
+  // It succeeds.  The retry time is not updated, so it should remain at t5.
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+
+  // Another sync cycle.  This one is still before the scheduled retry.  It does
+  // not change the scheduled retry time.
+  nudge_tracker_.SetSyncCycleStartTime(t4);
+  EXPECT_FALSE(nudge_tracker_.IsRetryRequired());
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+
+  // The retry scheduled way back during the first cycle of this test finally
+  // becomes due.  Perform a successful sync cycle to service it.
+  nudge_tracker_.SetSyncCycleStartTime(t6);
+  EXPECT_TRUE(nudge_tracker_.IsRetryRequired());
+  nudge_tracker_.RecordSuccessfulSyncCycle();
+}
+
+// Test the default nudge delays for various types.
+TEST_F(NudgeTrackerTest, NudgeDelayTest) {
+  // Set to a known value to compare against.
+  nudge_tracker_.SetDefaultNudgeDelay(base::TimeDelta());
+
+  // Bookmarks and preference both have "slow nudge" delays.
+  EXPECT_EQ(nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS)),
+            nudge_tracker_.RecordLocalChange(ModelTypeSet(PREFERENCES)));
+
+  // Typed URLs has a default delay.
+  EXPECT_EQ(nudge_tracker_.RecordLocalChange(ModelTypeSet(TYPED_URLS)),
+            base::TimeDelta());
+
+  // "Slow nudge" delays are longer than the default.
+  EXPECT_GT(nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS)),
+            base::TimeDelta());
+
+  // Sessions is longer than "slow nudge".
+  EXPECT_GT(nudge_tracker_.RecordLocalChange(ModelTypeSet(SESSIONS)),
+            nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS)));
+
+  // Favicons have the same delay as sessions.
+  EXPECT_EQ(nudge_tracker_.RecordLocalChange(ModelTypeSet(SESSIONS)),
+            nudge_tracker_.RecordLocalChange(ModelTypeSet(FAVICON_TRACKING)));
+
+  // Autofill has the longer delay of all.
+  EXPECT_GT(nudge_tracker_.RecordLocalChange(ModelTypeSet(AUTOFILL)),
+            nudge_tracker_.RecordLocalChange(ModelTypeSet(SESSIONS)));
+
+  // A nudge with no types takes the longest delay.
+  EXPECT_EQ(nudge_tracker_.RecordLocalChange(ModelTypeSet(AUTOFILL)),
+            nudge_tracker_.RecordLocalChange(ModelTypeSet()));
+
+  // The actual nudge delay should be the shortest of the set.
+  EXPECT_EQ(
+      nudge_tracker_.RecordLocalChange(ModelTypeSet(TYPED_URLS)),
+      nudge_tracker_.RecordLocalChange(ModelTypeSet(TYPED_URLS, AUTOFILL)));
+}
+
+// Test that custom nudge delays are used over the defaults.
+TEST_F(NudgeTrackerTest, CustomDelayTest) {
+  // Set some custom delays.
+  std::map<ModelType, base::TimeDelta> delay_map;
+  delay_map[BOOKMARKS] = base::TimeDelta::FromSeconds(10);
+  delay_map[SESSIONS] = base::TimeDelta::FromSeconds(2);
+  nudge_tracker_.OnReceivedCustomNudgeDelays(delay_map);
+
+  // Only those with custom delays should be affected, not another type.
+  EXPECT_NE(nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS)),
+            nudge_tracker_.RecordLocalChange(ModelTypeSet(PREFERENCES)));
+
+  EXPECT_EQ(base::TimeDelta::FromSeconds(10),
+            nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS)));
+  EXPECT_EQ(base::TimeDelta::FromSeconds(2),
+            nudge_tracker_.RecordLocalChange(ModelTypeSet(SESSIONS)));
+}
+
+// Check that custom nudge delays can never result in a value shorter than the
+// minimum nudge delay.
+TEST_F(NudgeTrackerTest, NoTypesShorterThanDefault) {
+  // Set delay to a known value.
+  nudge_tracker_.SetDefaultNudgeDelay(base::TimeDelta::FromMilliseconds(500));
+
+  std::map<ModelType, base::TimeDelta> delay_map;
+  ModelTypeSet protocol_types = syncer::ProtocolTypes();
+  for (ModelTypeSet::Iterator iter = protocol_types.First(); iter.Good();
+       iter.Inc()) {
+    delay_map[iter.Get()] = base::TimeDelta();
+  }
+  nudge_tracker_.OnReceivedCustomNudgeDelays(delay_map);
+
+  // All types should still have a nudge greater than or equal to the minimum.
+  for (ModelTypeSet::Iterator iter = protocol_types.First(); iter.Good();
+       iter.Inc()) {
+    EXPECT_GE(nudge_tracker_.RecordLocalChange(ModelTypeSet(iter.Get())),
+              base::TimeDelta::FromMilliseconds(500));
+  }
+}
+
+class NudgeTrackerAckTrackingTest : public NudgeTrackerTest {
+ public:
+  NudgeTrackerAckTrackingTest() {}
+
+  bool IsInvalidationUnacknowledged(int tracking_id) {
+    return tracker_.IsUnacked(tracking_id);
+  }
+
+  bool IsInvalidationAcknowledged(int tracking_id) {
+    return tracker_.IsAcknowledged(tracking_id);
+  }
+
+  bool IsInvalidationDropped(int tracking_id) {
+    return tracker_.IsDropped(tracking_id);
+  }
+
+  int SendInvalidation(ModelType type, int version, const std::string& hint) {
+    // Build and register the invalidation.
+    scoped_ptr<TrackableMockInvalidation> inv =
+        tracker_.IssueInvalidation(version, hint);
+    int id = inv->GetTrackingId();
+
+    // Send it to the NudgeTracker.
+    nudge_tracker_.RecordRemoteInvalidation(type, inv.Pass());
+
+    // Return its ID to the test framework for use in assertions.
+    return id;
+  }
+
+  int SendUnknownVersionInvalidation(ModelType type) {
+    // Build and register the invalidation.
+    scoped_ptr<TrackableMockInvalidation> inv =
+        tracker_.IssueUnknownVersionInvalidation();
+    int id = inv->GetTrackingId();
+
+    // Send it to the NudgeTracker.
+    nudge_tracker_.RecordRemoteInvalidation(type, inv.Pass());
+
+    // Return its ID to the test framework for use in assertions.
+    return id;
+  }
+
+  bool AllInvalidationsAccountedFor() const {
+    return tracker_.AllInvalidationsAccountedFor();
+  }
+
+  void RecordSuccessfulSyncCycle() {
+    nudge_tracker_.RecordSuccessfulSyncCycle();
+  }
+
+ private:
+  MockInvalidationTracker tracker_;
+};
+
+// Test the acknowledgement of a single invalidation.
+TEST_F(NudgeTrackerAckTrackingTest, SimpleAcknowledgement) {
+  int inv_id = SendInvalidation(BOOKMARKS, 10, "hint");
+
+  EXPECT_TRUE(IsInvalidationUnacknowledged(inv_id));
+
+  RecordSuccessfulSyncCycle();
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv_id));
+
+  EXPECT_TRUE(AllInvalidationsAccountedFor());
+}
+
+// Test the acknowledgement of many invalidations.
+TEST_F(NudgeTrackerAckTrackingTest, ManyAcknowledgements) {
+  int inv1_id = SendInvalidation(BOOKMARKS, 10, "hint");
+  int inv2_id = SendInvalidation(BOOKMARKS, 14, "hint2");
+  int inv3_id = SendInvalidation(PREFERENCES, 8, "hint3");
+
+  EXPECT_TRUE(IsInvalidationUnacknowledged(inv1_id));
+  EXPECT_TRUE(IsInvalidationUnacknowledged(inv2_id));
+  EXPECT_TRUE(IsInvalidationUnacknowledged(inv3_id));
+
+  RecordSuccessfulSyncCycle();
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv1_id));
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv2_id));
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv3_id));
+
+  EXPECT_TRUE(AllInvalidationsAccountedFor());
+}
+
+// Test dropping when the buffer overflows and subsequent drop recovery.
+TEST_F(NudgeTrackerAckTrackingTest, OverflowAndRecover) {
+  std::vector<int> invalidation_ids;
+
+  int inv10_id = SendInvalidation(BOOKMARKS, 10, "hint");
+  for (size_t i = 1; i < GetHintBufferSize(); ++i) {
+    invalidation_ids.push_back(SendInvalidation(BOOKMARKS, i + 10, "hint"));
+  }
+
+  for (std::vector<int>::iterator it = invalidation_ids.begin();
+       it != invalidation_ids.end();
+       ++it) {
+    EXPECT_TRUE(IsInvalidationUnacknowledged(*it));
+  }
+
+  // This invalidation, though arriving the most recently, has the oldest
+  // version number so it should be dropped first.
+  int inv5_id = SendInvalidation(BOOKMARKS, 5, "old_hint");
+  EXPECT_TRUE(IsInvalidationDropped(inv5_id));
+
+  // This invalidation has a larger version number, so it will force a
+  // previously delivered invalidation to be dropped.
+  int inv100_id = SendInvalidation(BOOKMARKS, 100, "new_hint");
+  EXPECT_TRUE(IsInvalidationDropped(inv10_id));
+
+  // This should recover from the drop and bring us back into sync.
+  RecordSuccessfulSyncCycle();
+
+  for (std::vector<int>::iterator it = invalidation_ids.begin();
+       it != invalidation_ids.end();
+       ++it) {
+    EXPECT_TRUE(IsInvalidationAcknowledged(*it));
+  }
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv100_id));
+
+  EXPECT_TRUE(AllInvalidationsAccountedFor());
+}
+
+// Test receipt of an unknown version invalidation from the server.
+TEST_F(NudgeTrackerAckTrackingTest, UnknownVersionFromServer_Simple) {
+  int inv_id = SendUnknownVersionInvalidation(BOOKMARKS);
+  EXPECT_TRUE(IsInvalidationUnacknowledged(inv_id));
+  RecordSuccessfulSyncCycle();
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv_id));
+  EXPECT_TRUE(AllInvalidationsAccountedFor());
+}
+
+// Test receipt of multiple unknown version invalidations from the server.
+TEST_F(NudgeTrackerAckTrackingTest, UnknownVersionFromServer_Complex) {
+  int inv1_id = SendUnknownVersionInvalidation(BOOKMARKS);
+  int inv2_id = SendInvalidation(BOOKMARKS, 10, "hint");
+  int inv3_id = SendUnknownVersionInvalidation(BOOKMARKS);
+  int inv4_id = SendUnknownVersionInvalidation(BOOKMARKS);
+  int inv5_id = SendInvalidation(BOOKMARKS, 20, "hint2");
+
+  // These invalidations have been overridden, so they got acked early.
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv1_id));
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv3_id));
+
+  // These invalidations are still waiting to be used.
+  EXPECT_TRUE(IsInvalidationUnacknowledged(inv2_id));
+  EXPECT_TRUE(IsInvalidationUnacknowledged(inv4_id));
+  EXPECT_TRUE(IsInvalidationUnacknowledged(inv5_id));
+
+  // Finish the sync cycle and expect all remaining invalidations to be acked.
+  RecordSuccessfulSyncCycle();
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv1_id));
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv2_id));
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv3_id));
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv4_id));
+  EXPECT_TRUE(IsInvalidationAcknowledged(inv5_id));
+
+  EXPECT_TRUE(AllInvalidationsAccountedFor());
+}
+
 }  // namespace sessions
 }  // namespace syncer