src/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.cpp

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  12  *     documentation and/or other materials provided with the distribution.
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  17  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
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  25
  26 #include "config.h"
  27
  28 #include "platform/graphics/Canvas2DLayerBridge.h"
  29
  30 #include "GrContext.h"
  31 #include "SkDevice.h"
  32 #include "SkSurface.h"
  33 #include "platform/TraceEvent.h"
  34 #include "platform/graphics/Canvas2DLayerManager.h"
  35 #include "platform/graphics/GraphicsLayer.h"
  36 #include "public/platform/Platform.h"
  37 #include "public/platform/WebCompositorSupport.h"
  38 #include "public/platform/WebGraphicsContext3D.h"
  39 #include "public/platform/WebGraphicsContext3DProvider.h"
  40 #include "wtf/RefCountedLeakCounter.h"
  41
  42 namespace {
  43 enum {
  44     InvalidMailboxIndex = -1,
  45 };
  46
  47 DEFINE_DEBUG_ONLY_GLOBAL(WTF::RefCountedLeakCounter, canvas2DLayerBridgeInstanceCounter, ("Canvas2DLayerBridge"));
  48 }
  49
  50 namespace blink {
  51
  52 static PassRefPtr<SkSurface> createSkSurface(GrContext* gr, const IntSize& size, int msaaSampleCount = 0)
  53 {
  54     if (!gr)
  55         return nullptr;
  56     gr->resetContext();
  57     SkImageInfo info = SkImageInfo::MakeN32Premul(size.width(), size.height());
  58     return adoptRef(SkSurface::NewRenderTarget(gr, info,  msaaSampleCount));
  59 }
  60
  61 PassRefPtr<Canvas2DLayerBridge> Canvas2DLayerBridge::create(const IntSize& size, OpacityMode opacityMode, int msaaSampleCount)
  62 {
  63     TRACE_EVENT_INSTANT0("test_gpu", "Canvas2DLayerBridgeCreation");
  64     OwnPtr<WebGraphicsContext3DProvider> contextProvider = adoptPtr(Platform::current()->createSharedOffscreenGraphicsContext3DProvider());
  65     if (!contextProvider)
  66         return nullptr;
  67     RefPtr<SkSurface> surface(createSkSurface(contextProvider->grContext(), size, msaaSampleCount));
  68     if (!surface)
  69         return nullptr;
  70     RefPtr<Canvas2DLayerBridge> layerBridge;
  71     OwnPtr<SkDeferredCanvas> canvas = adoptPtr(SkDeferredCanvas::Create(surface.get()));
  72     layerBridge = adoptRef(new Canvas2DLayerBridge(contextProvider.release(), canvas.release(), surface.release(), msaaSampleCount, opacityMode));
  73     return layerBridge.release();
  74 }
  75
  76 Canvas2DLayerBridge::Canvas2DLayerBridge(PassOwnPtr<WebGraphicsContext3DProvider> contextProvider, PassOwnPtr<SkDeferredCanvas> canvas, PassRefPtr<SkSurface> surface, int msaaSampleCount, OpacityMode opacityMode)
  77     : m_canvas(canvas)
  78     , m_surface(surface)
  79     , m_contextProvider(contextProvider)
  80     , m_imageBuffer(0)
  81     , m_msaaSampleCount(msaaSampleCount)
  82     , m_bytesAllocated(0)
  83     , m_didRecordDrawCommand(false)
  84     , m_isSurfaceValid(true)
  85     , m_framesPending(0)
  86     , m_framesSinceMailboxRelease(0)
  87     , m_destructionInProgress(false)
  88     , m_rateLimitingEnabled(false)
  89     , m_isHidden(false)
  90     , m_next(0)
  91     , m_prev(0)
  92     , m_lastImageId(0)
  93     , m_releasedMailboxInfoIndex(InvalidMailboxIndex)
  94 {
  95     ASSERT(m_canvas);
  96     ASSERT(m_surface);
  97     ASSERT(m_contextProvider);
  98     // Used by browser tests to detect the use of a Canvas2DLayerBridge.
  99     TRACE_EVENT_INSTANT0("test_gpu", "Canvas2DLayerBridgeCreation");
 100     m_layer = adoptPtr(Platform::current()->compositorSupport()->createExternalTextureLayer(this));
 101     m_layer->setOpaque(opacityMode == Opaque);
 102     m_layer->setBlendBackgroundColor(opacityMode != Opaque);
 103     GraphicsLayer::registerContentsLayer(m_layer->layer());
 104     m_layer->setRateLimitContext(m_rateLimitingEnabled);
 105     m_canvas->setNotificationClient(this);
 106 #ifndef NDEBUG
 107     canvas2DLayerBridgeInstanceCounter.increment();
 108 #endif
 109 }
 110
 111 Canvas2DLayerBridge::~Canvas2DLayerBridge()
 112 {
 113     ASSERT(m_destructionInProgress);
 114     ASSERT(!Canvas2DLayerManager::get().isInList(this));
 115     m_layer.clear();
 116     freeReleasedMailbox();
 117 #if ENABLE(ASSERT)
 118     Vector<MailboxInfo>::iterator mailboxInfo;
 119     for (mailboxInfo = m_mailboxes.begin(); mailboxInfo < m_mailboxes.end(); ++mailboxInfo) {
 120         ASSERT(mailboxInfo->m_status != MailboxInUse);
 121         ASSERT(mailboxInfo->m_status != MailboxReleased || m_contextProvider->context3d()->isContextLost() || !m_isSurfaceValid);
 122     }
 123 #endif
 124     m_mailboxes.clear();
 125 #ifndef NDEBUG
 126     canvas2DLayerBridgeInstanceCounter.decrement();
 127 #endif
 128 }
 129
 130 void Canvas2DLayerBridge::beginDestruction()
 131 {
 132     ASSERT(!m_destructionInProgress);
 133     setRateLimitingEnabled(false);
 134     m_canvas->silentFlush();
 135     m_imageBuffer = 0;
 136     freeTransientResources();
 137     setIsHidden(true);
 138     m_destructionInProgress = true;
 139     GraphicsLayer::unregisterContentsLayer(m_layer->layer());
 140     m_canvas->setNotificationClient(0);
 141     m_surface.clear();
 142     m_canvas.clear();
 143     m_layer->clearTexture();
 144     // Orphaning the layer is required to trigger the recration of a new layer
 145     // in the case where destruction is caused by a canvas resize. Test:
 146     // virtual/gpu/fast/canvas/canvas-resize-after-paint-without-layout.html
 147     m_layer->layer()->removeFromParent();
 148     // To anyone who ever hits this assert: Please update crbug.com/344666
 149     // with repro steps.
 150     ASSERT(!m_bytesAllocated);
 151 }
 152
 153 void Canvas2DLayerBridge::setIsHidden(bool hidden)
 154 {
 155     ASSERT(!m_destructionInProgress);
 156     bool newHiddenValue = hidden || m_destructionInProgress;
 157     if (m_isHidden == newHiddenValue)
 158         return;
 159
 160     m_isHidden = newHiddenValue;
 161     if (isHidden()) {
 162         freeTransientResources();
 163     }
 164 }
 165
 166 void Canvas2DLayerBridge::willAccessPixels()
 167 {
 168     // A readback operation may alter the texture parameters, which may affect
 169     // the compositor's behavior. Therefore, we must trigger copy-on-write
 170     // even though we are not technically writing to the texture, only to its
 171     // parameters.
 172     m_surface->notifyContentWillChange(SkSurface::kRetain_ContentChangeMode);
 173 }
 174
 175 void Canvas2DLayerBridge::freeTransientResources()
 176 {
 177     ASSERT(!m_destructionInProgress);
 178     if (!m_isSurfaceValid)
 179         return;
 180     freeReleasedMailbox();
 181     flush();
 182     freeMemoryIfPossible(bytesAllocated());
 183     ASSERT(!hasTransientResources());
 184 }
 185
 186 bool Canvas2DLayerBridge::hasTransientResources() const
 187 {
 188     return !m_destructionInProgress && (hasReleasedMailbox() || bytesAllocated());
 189 }
 190
 191 void Canvas2DLayerBridge::limitPendingFrames()
 192 {
 193     ASSERT(!m_destructionInProgress);
 194     if (isHidden()) {
 195         freeTransientResources();
 196         return;
 197     }
 198     if (m_didRecordDrawCommand) {
 199         m_framesPending++;
 200         m_didRecordDrawCommand = false;
 201         if (m_framesPending > 1) {
 202             // Turn on the rate limiter if this layer tends to accumulate a
 203             // non-discardable multi-frame backlog of draw commands.
 204             setRateLimitingEnabled(true);
 205         }
 206         if (m_rateLimitingEnabled) {
 207             flush();
 208         }
 209     }
 210     ++m_framesSinceMailboxRelease;
 211     if (releasedMailboxHasExpired()) {
 212         freeReleasedMailbox();
 213     }
 214 }
 215
 216 void Canvas2DLayerBridge::prepareForDraw()
 217 {
 218     ASSERT(!m_destructionInProgress);
 219     ASSERT(m_layer);
 220     if (!checkSurfaceValid()) {
 221         if (m_canvas) {
 222             // drop pending commands because there is no surface to draw to
 223             m_canvas->silentFlush();
 224         }
 225         return;
 226     }
 227 }
 228
 229 void Canvas2DLayerBridge::storageAllocatedForRecordingChanged(size_t bytesAllocated)
 230 {
 231     ASSERT(!m_destructionInProgress);
 232     intptr_t delta = (intptr_t)bytesAllocated - (intptr_t)m_bytesAllocated;
 233     m_bytesAllocated = bytesAllocated;
 234     Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this, delta);
 235 }
 236
 237 size_t Canvas2DLayerBridge::storageAllocatedForRecording()
 238 {
 239     return m_canvas->storageAllocatedForRecording();
 240 }
 241
 242 void Canvas2DLayerBridge::flushedDrawCommands()
 243 {
 244     ASSERT(!m_destructionInProgress);
 245     storageAllocatedForRecordingChanged(storageAllocatedForRecording());
 246     m_framesPending = 0;
 247 }
 248
 249 void Canvas2DLayerBridge::skippedPendingDrawCommands()
 250 {
 251     ASSERT(!m_destructionInProgress);
 252     // Stop triggering the rate limiter if SkDeferredCanvas is detecting
 253     // and optimizing overdraw.
 254     setRateLimitingEnabled(false);
 255     flushedDrawCommands();
 256 }
 257
 258 void Canvas2DLayerBridge::setRateLimitingEnabled(bool enabled)
 259 {
 260     ASSERT(!m_destructionInProgress);
 261     if (m_rateLimitingEnabled != enabled) {
 262         m_rateLimitingEnabled = enabled;
 263         m_layer->setRateLimitContext(m_rateLimitingEnabled);
 264     }
 265 }
 266
 267 size_t Canvas2DLayerBridge::freeMemoryIfPossible(size_t bytesToFree)
 268 {
 269     ASSERT(!m_destructionInProgress);
 270     size_t bytesFreed = m_canvas->freeMemoryIfPossible(bytesToFree);
 271     m_bytesAllocated -= bytesFreed;
 272     if (bytesFreed)
 273         Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this, -((intptr_t)bytesFreed));
 274     return bytesFreed;
 275 }
 276
 277 void Canvas2DLayerBridge::flush()
 278 {
 279     ASSERT(!m_destructionInProgress);
 280     if (m_canvas->hasPendingCommands()) {
 281         TRACE_EVENT0("cc", "Canvas2DLayerBridge::flush");
 282         freeReleasedMailbox(); // To avoid unnecessary triple-buffering
 283         m_canvas->flush();
 284     }
 285 }
 286
 287 bool Canvas2DLayerBridge::releasedMailboxHasExpired()
 288 {
 289     // This heuristic indicates that the canvas is not being
 290     // actively presented by the compositor (3 frames rendered since
 291     // last mailbox release), suggesting that double buffering is not required.
 292     return hasReleasedMailbox() && m_framesSinceMailboxRelease > 2;
 293 }
 294
 295 Canvas2DLayerBridge::MailboxInfo* Canvas2DLayerBridge::releasedMailboxInfo()
 296 {
 297     return hasReleasedMailbox() ? &m_mailboxes[m_releasedMailboxInfoIndex] : 0;
 298 }
 299
 300 bool Canvas2DLayerBridge::hasReleasedMailbox() const
 301 {
 302     return m_releasedMailboxInfoIndex != InvalidMailboxIndex;
 303 }
 304
 305 void Canvas2DLayerBridge::freeReleasedMailbox()
 306 {
 307     if (!m_isSurfaceValid || m_contextProvider->context3d()->isContextLost())
 308         return;
 309     MailboxInfo* mailboxInfo = releasedMailboxInfo();
 310     if (!mailboxInfo)
 311         return;
 312
 313     ASSERT(mailboxInfo->m_status == MailboxReleased);
 314     if (mailboxInfo->m_mailbox.syncPoint) {
 315         context()->waitSyncPoint(mailboxInfo->m_mailbox.syncPoint);
 316         mailboxInfo->m_mailbox.syncPoint = 0;
 317     }
 318     // Invalidate texture state in case the compositor altered it since the copy-on-write.
 319     if (mailboxInfo->m_image) {
 320         if (isHidden() || releasedMailboxHasExpired())
 321             mailboxInfo->m_image->getTexture()->resetFlag(static_cast<GrTextureFlags>(GrTexture::kReturnToCache_FlagBit));
 322         mailboxInfo->m_image->getTexture()->textureParamsModified();
 323         mailboxInfo->m_image.clear();
 324     }
 325     mailboxInfo->m_status = MailboxAvailable;
 326     m_releasedMailboxInfoIndex = InvalidMailboxIndex;
 327     Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 328 }
 329
 330 WebGraphicsContext3D* Canvas2DLayerBridge::context()
 331 {
 332     // Check on m_layer is necessary because context() may be called during
 333     // the destruction of m_layer
 334     if (m_layer && !m_destructionInProgress)
 335         checkSurfaceValid(); // To ensure rate limiter is disabled if context is lost.
 336     return m_contextProvider ? m_contextProvider->context3d() : 0;
 337 }
 338
 339 bool Canvas2DLayerBridge::checkSurfaceValid()
 340 {
 341     ASSERT(!m_destructionInProgress);
 342     if (m_destructionInProgress || !m_isSurfaceValid)
 343         return false;
 344     if (m_contextProvider->context3d()->isContextLost()) {
 345         m_isSurfaceValid = false;
 346         m_surface.clear();
 347         if (m_imageBuffer)
 348             m_imageBuffer->notifySurfaceInvalid();
 349         setRateLimitingEnabled(false);
 350     }
 351     return m_isSurfaceValid;
 352 }
 353
 354 bool Canvas2DLayerBridge::restoreSurface()
 355 {
 356     ASSERT(!m_destructionInProgress);
 357     if (m_destructionInProgress)
 358         return false;
 359     ASSERT(m_layer && !m_isSurfaceValid);
 360
 361     WebGraphicsContext3D* sharedContext = 0;
 362     // We must clear the mailboxes before calling m_layer->clearTexture() to prevent
 363     // re-entry via mailboxReleased from operating on defunct GrContext objects.
 364     m_mailboxes.clear();
 365     m_releasedMailboxInfoIndex = InvalidMailboxIndex;
 366     m_layer->clearTexture();
 367     m_contextProvider = adoptPtr(Platform::current()->createSharedOffscreenGraphicsContext3DProvider());
 368     if (m_contextProvider)
 369         sharedContext = m_contextProvider->context3d();
 370
 371     if (sharedContext && !sharedContext->isContextLost()) {
 372         IntSize size(m_canvas->getTopDevice()->width(), m_canvas->getTopDevice()->height());
 373         RefPtr<SkSurface> surface(createSkSurface(m_contextProvider->grContext(), size, m_msaaSampleCount));
 374         if (surface.get()) {
 375             m_surface = surface.release();
 376             m_canvas->setSurface(m_surface.get());
 377             m_isSurfaceValid = true;
 378             // FIXME: draw sad canvas picture into new buffer crbug.com/243842
 379         }
 380     }
 381
 382     return m_isSurfaceValid;
 383 }
 384
 385 bool Canvas2DLayerBridge::prepareMailbox(WebExternalTextureMailbox* outMailbox, WebExternalBitmap* bitmap)
 386 {
 387     if (m_destructionInProgress) {
 388         // It can be hit in the following sequence.
 389         // 1. Canvas draws something.
 390         // 2. The compositor begins the frame.
 391         // 3. Javascript makes a context be lost.
 392         // 4. Here.
 393         return false;
 394     }
 395     if (bitmap) {
 396         // Using accelerated 2d canvas with software renderer, which
 397         // should only happen in tests that use fake graphics contexts
 398         // or in Android WebView in software mode. In this case, we do
 399         // not care about producing any results for this canvas.
 400         m_canvas->silentFlush();
 401         m_lastImageId = 0;
 402         return false;
 403     }
 404     if (!checkSurfaceValid())
 405         return false;
 406
 407     WebGraphicsContext3D* webContext = context();
 408
 409     // Release to skia textures that were previouosly released by the
 410     // compositor. We do this before acquiring the next snapshot in
 411     // order to cap maximum gpu memory consumption.
 412     flush();
 413
 414     RefPtr<SkImage> image = adoptRef(m_canvas->newImageSnapshot());
 415
 416     // Early exit if canvas was not drawn to since last prepareMailbox
 417     if (image->uniqueID() == m_lastImageId)
 418         return false;
 419     m_lastImageId = image->uniqueID();
 420
 421     MailboxInfo* mailboxInfo = createMailboxInfo();
 422     mailboxInfo->m_status = MailboxInUse;
 423     mailboxInfo->m_image = image;
 424
 425     ASSERT(mailboxInfo->m_mailbox.syncPoint == 0);
 426     ASSERT(mailboxInfo->m_image.get());
 427
 428     // set m_parentLayerBridge to make sure 'this' stays alive as long as it has
 429     // live mailboxes
 430     ASSERT(!mailboxInfo->m_parentLayerBridge);
 431     mailboxInfo->m_parentLayerBridge = this;
 432     *outMailbox = mailboxInfo->m_mailbox;
 433
 434     GrContext* grContext = m_contextProvider->grContext();
 435     if (!grContext)
 436         return true; // for testing: skip gl stuff when using a mock graphics context.
 437
 438     ASSERT(mailboxInfo->m_image->getTexture());
 439
 440     // Because of texture sharing with the compositor, we must invalidate
 441     // the state cached in skia so that the deferred copy on write
 442     // in SkSurface_Gpu does not make any false assumptions.
 443     mailboxInfo->m_image->getTexture()->textureParamsModified();
 444
 445     webContext->bindTexture(GL_TEXTURE_2D, mailboxInfo->m_image->getTexture()->getTextureHandle());
 446     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 447     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 448     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 449     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 450     webContext->produceTextureCHROMIUM(GL_TEXTURE_2D, mailboxInfo->m_mailbox.name);
 451     if (isHidden()) {
 452         // With hidden canvases, we release the SkImage immediately because
 453         // there is no need for animations to be double buffered.
 454         mailboxInfo->m_image.clear();
 455     } else {
 456         webContext->flush();
 457         mailboxInfo->m_mailbox.syncPoint = webContext->insertSyncPoint();
 458     }
 459     webContext->bindTexture(GL_TEXTURE_2D, 0);
 460     // Because we are changing the texture binding without going through skia,
 461     // we must dirty the context.
 462     grContext->resetContext(kTextureBinding_GrGLBackendState);
 463
 464     return true;
 465 }
 466
 467 Canvas2DLayerBridge::MailboxInfo* Canvas2DLayerBridge::createMailboxInfo() {
 468     ASSERT(!m_destructionInProgress);
 469     MailboxInfo* mailboxInfo;
 470     for (mailboxInfo = m_mailboxes.begin(); mailboxInfo < m_mailboxes.end(); mailboxInfo++) {
 471         if (mailboxInfo->m_status == MailboxAvailable) {
 472             return mailboxInfo;
 473         }
 474     }
 475
 476     // No available mailbox: create one.
 477     m_mailboxes.grow(m_mailboxes.size() + 1);
 478     mailboxInfo = &m_mailboxes.last();
 479     context()->genMailboxCHROMIUM(mailboxInfo->m_mailbox.name);
 480     // Worst case, canvas is triple buffered.  More than 3 active mailboxes
 481     // means there is a problem.
 482     // For the single-threaded case, this value needs to be at least
 483     // kMaxSwapBuffersPending+1 (in render_widget.h).
 484     // Because of crbug.com/247874, it needs to be kMaxSwapBuffersPending+2.
 485     // TODO(piman): fix this.
 486     ASSERT(m_mailboxes.size() <= 4);
 487     ASSERT(mailboxInfo < m_mailboxes.end());
 488     return mailboxInfo;
 489 }
 490
 491 void Canvas2DLayerBridge::mailboxReleased(const WebExternalTextureMailbox& mailbox, bool lostResource)
 492 {
 493     freeReleasedMailbox(); // Never have more than one mailbox in the released state.
 494     bool contextLost = !m_isSurfaceValid || m_contextProvider->context3d()->isContextLost();
 495     Vector<MailboxInfo>::iterator mailboxInfo;
 496     for (mailboxInfo = m_mailboxes.begin(); mailboxInfo < m_mailboxes.end(); ++mailboxInfo) {
 497         if (nameEquals(mailboxInfo->m_mailbox, mailbox)) {
 498             mailboxInfo->m_mailbox.syncPoint = mailbox.syncPoint;
 499             ASSERT(mailboxInfo->m_status == MailboxInUse);
 500             ASSERT(mailboxInfo->m_parentLayerBridge.get() == this);
 501
 502             if (contextLost) {
 503                 // No need to clean up the mailbox resource, but make sure the
 504                 // mailbox can also be reusable once the context is restored.
 505                 mailboxInfo->m_status = MailboxAvailable;
 506                 m_releasedMailboxInfoIndex = InvalidMailboxIndex;
 507                 Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 508             } else if (lostResource) {
 509                 // In case of the resource is lost, we need to delete the backing
 510                 // texture and remove the mailbox from list to avoid reusing it
 511                 // in future.
 512                 if (mailboxInfo->m_image) {
 513                     GrTexture* texture = mailboxInfo->m_image->getTexture();
 514                     if (texture) {
 515                         texture->resetFlag(static_cast<GrTextureFlags>(GrTexture::kReturnToCache_FlagBit));
 516                         texture->textureParamsModified();
 517                     }
 518                     mailboxInfo->m_image.clear();
 519                 }
 520                 if (m_destructionInProgress) {
 521                     mailboxInfo->m_status = MailboxAvailable; // To satisfy assert in destructor
 522
 523                     // The following line may trigger self destruction. We do not care about
 524                     // not cleaning up m_mailboxes during destruction sequence because
 525                     // mailboxes will not be recycled after this point. Calling remove()
 526                     // could trigger a memory use after free, so we just clear the self
 527                     // reference to be safe, and we let the Canvas2DLayerBridge destructor
 528                     // take care of freeing m_mailboxes.
 529                     mailboxInfo->m_parentLayerBridge.clear();
 530                 } else {
 531                     size_t i = mailboxInfo - m_mailboxes.begin();
 532                     m_mailboxes.remove(i); // indirectly clears mailboxInfo->m_parentLayerBridge
 533                     Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 534                 }
 535                 // mailboxInfo is not valid from this point, so we return immediately.
 536                 return;
 537             } else {
 538                 mailboxInfo->m_status = MailboxReleased;
 539                 m_releasedMailboxInfoIndex = mailboxInfo - m_mailboxes.begin();
 540                 m_framesSinceMailboxRelease = 0;
 541                 if (isHidden()) {
 542                     freeReleasedMailbox();
 543                 } else {
 544                     ASSERT(!m_destructionInProgress);
 545                     Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 546                 }
 547             }
 548             // Trigger Canvas2DLayerBridge self-destruction if this is the
 549             // last live mailbox and the layer bridge is not externally
 550             // referenced.
 551             mailboxInfo->m_parentLayerBridge.clear();
 552             return;
 553         }
 554     }
 555 }
 556
 557 WebLayer* Canvas2DLayerBridge::layer() const
 558 {
 559     ASSERT(!m_destructionInProgress);
 560     ASSERT(m_layer);
 561     return m_layer->layer();
 562 }
 563
 564 void Canvas2DLayerBridge::finalizeFrame(const FloatRect &dirtyRect)
 565 {
 566     ASSERT(!m_destructionInProgress);
 567     Canvas2DLayerManager::get().layerDidDraw(this);
 568     m_layer->layer()->invalidateRect(dirtyRect);
 569     m_didRecordDrawCommand = true;
 570 }
 571
 572 Platform3DObject Canvas2DLayerBridge::getBackingTexture()
 573 {
 574     ASSERT(!m_destructionInProgress);
 575     if (!checkSurfaceValid())
 576         return 0;
 577     m_canvas->flush();
 578     context()->flush();
 579     GrRenderTarget* renderTarget = m_canvas->getTopDevice()->accessRenderTarget();
 580     if (renderTarget) {
 581         return renderTarget->asTexture()->getTextureHandle();
 582     }
 583     return 0;
 584 }
 585
 586 Canvas2DLayerBridge::MailboxInfo::MailboxInfo(const MailboxInfo& other) {
 587     // This copy constructor should only be used for Vector reallocation
 588     // Assuming 'other' is to be destroyed, we transfer m_image and
 589     // m_parentLayerBridge ownership rather than do a refcount dance.
 590     memcpy(&m_mailbox, &other.m_mailbox, sizeof(m_mailbox));
 591     m_image = const_cast<MailboxInfo*>(&other)->m_image.release();
 592     m_parentLayerBridge = const_cast<MailboxInfo*>(&other)->m_parentLayerBridge.release();
 593     m_status = other.m_status;
 594 }
 595
 596 } // namespace blink