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

   1 /*
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   9  *     notice, this list of conditions and the following disclaimer.
  10  * 2.  Redistributions in binary form must reproduce the above copyright
  11  *     notice, this list of conditions and the following disclaimer in the
  12  *     documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
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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     freeReleasedMailbox();
 179     flush();
 180     freeMemoryIfPossible(bytesAllocated());
 181     ASSERT(!hasTransientResources());
 182 }
 183
 184 bool Canvas2DLayerBridge::hasTransientResources() const
 185 {
 186     return !m_destructionInProgress && (hasReleasedMailbox() || bytesAllocated());
 187 }
 188
 189 void Canvas2DLayerBridge::limitPendingFrames()
 190 {
 191     ASSERT(!m_destructionInProgress);
 192     if (isHidden()) {
 193         freeTransientResources();
 194         return;
 195     }
 196     if (m_didRecordDrawCommand) {
 197         m_framesPending++;
 198         m_didRecordDrawCommand = false;
 199         if (m_framesPending > 1) {
 200             // Turn on the rate limiter if this layer tends to accumulate a
 201             // non-discardable multi-frame backlog of draw commands.
 202             setRateLimitingEnabled(true);
 203         }
 204         if (m_rateLimitingEnabled) {
 205             flush();
 206         }
 207     }
 208     ++m_framesSinceMailboxRelease;
 209     if (releasedMailboxHasExpired()) {
 210         freeReleasedMailbox();
 211     }
 212 }
 213
 214 void Canvas2DLayerBridge::prepareForDraw()
 215 {
 216     ASSERT(!m_destructionInProgress);
 217     ASSERT(m_layer);
 218     if (!checkSurfaceValid()) {
 219         if (m_canvas) {
 220             // drop pending commands because there is no surface to draw to
 221             m_canvas->silentFlush();
 222         }
 223         return;
 224     }
 225     context()->makeContextCurrent();
 226 }
 227
 228 void Canvas2DLayerBridge::storageAllocatedForRecordingChanged(size_t bytesAllocated)
 229 {
 230     ASSERT(!m_destructionInProgress);
 231     intptr_t delta = (intptr_t)bytesAllocated - (intptr_t)m_bytesAllocated;
 232     m_bytesAllocated = bytesAllocated;
 233     Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this, delta);
 234 }
 235
 236 size_t Canvas2DLayerBridge::storageAllocatedForRecording()
 237 {
 238     return m_canvas->storageAllocatedForRecording();
 239 }
 240
 241 void Canvas2DLayerBridge::flushedDrawCommands()
 242 {
 243     ASSERT(!m_destructionInProgress);
 244     storageAllocatedForRecordingChanged(storageAllocatedForRecording());
 245     m_framesPending = 0;
 246 }
 247
 248 void Canvas2DLayerBridge::skippedPendingDrawCommands()
 249 {
 250     ASSERT(!m_destructionInProgress);
 251     // Stop triggering the rate limiter if SkDeferredCanvas is detecting
 252     // and optimizing overdraw.
 253     setRateLimitingEnabled(false);
 254     flushedDrawCommands();
 255 }
 256
 257 void Canvas2DLayerBridge::setRateLimitingEnabled(bool enabled)
 258 {
 259     ASSERT(!m_destructionInProgress);
 260     if (m_rateLimitingEnabled != enabled) {
 261         m_rateLimitingEnabled = enabled;
 262         m_layer->setRateLimitContext(m_rateLimitingEnabled);
 263     }
 264 }
 265
 266 size_t Canvas2DLayerBridge::freeMemoryIfPossible(size_t bytesToFree)
 267 {
 268     ASSERT(!m_destructionInProgress);
 269     size_t bytesFreed = m_canvas->freeMemoryIfPossible(bytesToFree);
 270     m_bytesAllocated -= bytesFreed;
 271     if (bytesFreed)
 272         Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this, -((intptr_t)bytesFreed));
 273     return bytesFreed;
 274 }
 275
 276 void Canvas2DLayerBridge::flush()
 277 {
 278     ASSERT(!m_destructionInProgress);
 279     if (m_canvas->hasPendingCommands()) {
 280         TRACE_EVENT0("cc", "Canvas2DLayerBridge::flush");
 281         freeReleasedMailbox(); // To avoid unnecessary triple-buffering
 282         m_canvas->flush();
 283     }
 284 }
 285
 286 bool Canvas2DLayerBridge::releasedMailboxHasExpired()
 287 {
 288     // This heuristic indicates that the canvas is not being
 289     // actively presented by the compositor (3 frames rendered since
 290     // last mailbox release), suggesting that double buffering is not required.
 291     return hasReleasedMailbox() && m_framesSinceMailboxRelease > 2;
 292 }
 293
 294 Canvas2DLayerBridge::MailboxInfo* Canvas2DLayerBridge::releasedMailboxInfo()
 295 {
 296     return hasReleasedMailbox() ? &m_mailboxes[m_releasedMailboxInfoIndex] : 0;
 297 }
 298
 299 bool Canvas2DLayerBridge::hasReleasedMailbox() const
 300 {
 301     return m_releasedMailboxInfoIndex != InvalidMailboxIndex;
 302 }
 303
 304 void Canvas2DLayerBridge::freeReleasedMailbox()
 305 {
 306     if (!m_isSurfaceValid || m_contextProvider->context3d()->isContextLost())
 307         return;
 308     MailboxInfo* mailboxInfo = releasedMailboxInfo();
 309     if (!mailboxInfo)
 310         return;
 311
 312     ASSERT(mailboxInfo->m_status == MailboxReleased);
 313     if (mailboxInfo->m_mailbox.syncPoint) {
 314         context()->waitSyncPoint(mailboxInfo->m_mailbox.syncPoint);
 315         mailboxInfo->m_mailbox.syncPoint = 0;
 316     }
 317     // Invalidate texture state in case the compositor altered it since the copy-on-write.
 318     if (mailboxInfo->m_image) {
 319         if (isHidden() || releasedMailboxHasExpired())
 320             mailboxInfo->m_image->getTexture()->resetFlag(static_cast<GrTextureFlags>(GrTexture::kReturnToCache_FlagBit));
 321         mailboxInfo->m_image->getTexture()->textureParamsModified();
 322         mailboxInfo->m_image.clear();
 323     }
 324     mailboxInfo->m_status = MailboxAvailable;
 325     m_releasedMailboxInfoIndex = InvalidMailboxIndex;
 326     Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 327 }
 328
 329 WebGraphicsContext3D* Canvas2DLayerBridge::context()
 330 {
 331     // Check on m_layer is necessary because context() may be called during
 332     // the destruction of m_layer
 333     if (m_layer && !m_destructionInProgress)
 334         checkSurfaceValid(); // To ensure rate limiter is disabled if context is lost.
 335     return m_contextProvider ? m_contextProvider->context3d() : 0;
 336 }
 337
 338 bool Canvas2DLayerBridge::checkSurfaceValid()
 339 {
 340     ASSERT(!m_destructionInProgress);
 341     if (m_destructionInProgress || !m_isSurfaceValid)
 342         return false;
 343     if (m_contextProvider->context3d()->isContextLost()) {
 344         m_isSurfaceValid = false;
 345         m_surface.clear();
 346         if (m_imageBuffer)
 347             m_imageBuffer->notifySurfaceInvalid();
 348         setRateLimitingEnabled(false);
 349     }
 350     return m_isSurfaceValid;
 351 }
 352
 353 bool Canvas2DLayerBridge::restoreSurface()
 354 {
 355     ASSERT(!m_destructionInProgress);
 356     if (m_destructionInProgress)
 357         return false;
 358     ASSERT(m_layer && !m_isSurfaceValid);
 359
 360     WebGraphicsContext3D* sharedContext = 0;
 361     // We must clear the mailboxes before calling m_layer->clearTexture() to prevent
 362     // re-entry via mailboxReleased from operating on defunct GrContext objects.
 363     m_mailboxes.clear();
 364     m_releasedMailboxInfoIndex = InvalidMailboxIndex;
 365     m_layer->clearTexture();
 366     m_contextProvider = adoptPtr(Platform::current()->createSharedOffscreenGraphicsContext3DProvider());
 367     if (m_contextProvider)
 368         sharedContext = m_contextProvider->context3d();
 369
 370     if (sharedContext && !sharedContext->isContextLost()) {
 371         IntSize size(m_canvas->getTopDevice()->width(), m_canvas->getTopDevice()->height());
 372         RefPtr<SkSurface> surface(createSkSurface(m_contextProvider->grContext(), size, m_msaaSampleCount));
 373         if (surface.get()) {
 374             m_surface = surface.release();
 375             m_canvas->setSurface(m_surface.get());
 376             m_isSurfaceValid = true;
 377             // FIXME: draw sad canvas picture into new buffer crbug.com/243842
 378         }
 379     }
 380
 381     return m_isSurfaceValid;
 382 }
 383
 384 bool Canvas2DLayerBridge::prepareMailbox(WebExternalTextureMailbox* outMailbox, WebExternalBitmap* bitmap)
 385 {
 386     if (m_destructionInProgress) {
 387         // It can be hit in the following sequence.
 388         // 1. Canvas draws something.
 389         // 2. The compositor begins the frame.
 390         // 3. Javascript makes a context be lost.
 391         // 4. Here.
 392         return false;
 393     }
 394     if (bitmap) {
 395         // Using accelerated 2d canvas with software renderer, which
 396         // should only happen in tests that use fake graphics contexts
 397         // or in Android WebView in software mode. In this case, we do
 398         // not care about producing any results for this canvas.
 399         m_canvas->silentFlush();
 400         m_lastImageId = 0;
 401         return false;
 402     }
 403     if (!checkSurfaceValid())
 404         return false;
 405
 406     WebGraphicsContext3D* webContext = context();
 407
 408     // Release to skia textures that were previouosly released by the
 409     // compositor. We do this before acquiring the next snapshot in
 410     // order to cap maximum gpu memory consumption.
 411     webContext->makeContextCurrent();
 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     ASSERT(mailboxInfo->m_image->getTexture());
 428
 429     // Because of texture sharing with the compositor, we must invalidate
 430     // the state cached in skia so that the deferred copy on write
 431     // in SkSurface_Gpu does not make any false assumptions.
 432     mailboxInfo->m_image->getTexture()->textureParamsModified();
 433
 434     webContext->bindTexture(GL_TEXTURE_2D, mailboxInfo->m_image->getTexture()->getTextureHandle());
 435     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 436     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 437     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 438     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 439     webContext->produceTextureCHROMIUM(GL_TEXTURE_2D, mailboxInfo->m_mailbox.name);
 440     if (isHidden()) {
 441         // With hidden canvases, we release the SkImage immediately because
 442         // there is no need for animations to be double buffered.
 443         mailboxInfo->m_image.clear();
 444     } else {
 445         webContext->flush();
 446         mailboxInfo->m_mailbox.syncPoint = webContext->insertSyncPoint();
 447     }
 448     webContext->bindTexture(GL_TEXTURE_2D, 0);
 449     // Because we are changing the texture binding without going through skia,
 450     // we must dirty the context.
 451     m_contextProvider->grContext()->resetContext(kTextureBinding_GrGLBackendState);
 452
 453     // set m_parentLayerBridge to make sure 'this' stays alive as long as it has
 454     // live mailboxes
 455     ASSERT(!mailboxInfo->m_parentLayerBridge);
 456     mailboxInfo->m_parentLayerBridge = this;
 457     *outMailbox = mailboxInfo->m_mailbox;
 458
 459     return true;
 460 }
 461
 462 Canvas2DLayerBridge::MailboxInfo* Canvas2DLayerBridge::createMailboxInfo() {
 463     ASSERT(!m_destructionInProgress);
 464     MailboxInfo* mailboxInfo;
 465     for (mailboxInfo = m_mailboxes.begin(); mailboxInfo < m_mailboxes.end(); mailboxInfo++) {
 466         if (mailboxInfo->m_status == MailboxAvailable) {
 467             return mailboxInfo;
 468         }
 469     }
 470
 471     // No available mailbox: create one.
 472     m_mailboxes.grow(m_mailboxes.size() + 1);
 473     mailboxInfo = &m_mailboxes.last();
 474     context()->genMailboxCHROMIUM(mailboxInfo->m_mailbox.name);
 475     // Worst case, canvas is triple buffered.  More than 3 active mailboxes
 476     // means there is a problem.
 477     // For the single-threaded case, this value needs to be at least
 478     // kMaxSwapBuffersPending+1 (in render_widget.h).
 479     // Because of crbug.com/247874, it needs to be kMaxSwapBuffersPending+2.
 480     // TODO(piman): fix this.
 481     ASSERT(m_mailboxes.size() <= 4);
 482     ASSERT(mailboxInfo < m_mailboxes.end());
 483     return mailboxInfo;
 484 }
 485
 486 void Canvas2DLayerBridge::mailboxReleased(const WebExternalTextureMailbox& mailbox, bool lostResource)
 487 {
 488     freeReleasedMailbox(); // Never have more than one mailbox in the released state.
 489     bool contextLost = !m_isSurfaceValid || m_contextProvider->context3d()->isContextLost();
 490     Vector<MailboxInfo>::iterator mailboxInfo;
 491     for (mailboxInfo = m_mailboxes.begin(); mailboxInfo < m_mailboxes.end(); ++mailboxInfo) {
 492         if (nameEquals(mailboxInfo->m_mailbox, mailbox)) {
 493             mailboxInfo->m_mailbox.syncPoint = mailbox.syncPoint;
 494             ASSERT(mailboxInfo->m_status == MailboxInUse);
 495             ASSERT(mailboxInfo->m_parentLayerBridge.get() == this);
 496
 497             if (contextLost) {
 498                 // No need to clean up the mailbox resource, but make sure the
 499                 // mailbox can also be reusable once the context is restored.
 500                 mailboxInfo->m_status = MailboxAvailable;
 501                 m_releasedMailboxInfoIndex = InvalidMailboxIndex;
 502                 Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 503             } else if (lostResource) {
 504                 // In case of the resource is lost, we need to delete the backing
 505                 // texture and remove the mailbox from list to avoid reusing it
 506                 // in future.
 507                 if (mailboxInfo->m_image) {
 508                     mailboxInfo->m_image->getTexture()->resetFlag(
 509                         static_cast<GrTextureFlags>(GrTexture::kReturnToCache_FlagBit));
 510                     mailboxInfo->m_image->getTexture()->textureParamsModified();
 511                     mailboxInfo->m_image.clear();
 512                 }
 513                 size_t i = mailboxInfo - m_mailboxes.begin();
 514                 m_mailboxes.remove(i);
 515                 Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 516                 // Here we need to return early since mailboxInfo removal would
 517                 // also clear m_parentLayerBridge reference.
 518                 return;
 519             } else {
 520                 mailboxInfo->m_status = MailboxReleased;
 521                 m_releasedMailboxInfoIndex = mailboxInfo - m_mailboxes.begin();
 522                 m_framesSinceMailboxRelease = 0;
 523                 if (isHidden()) {
 524                     freeReleasedMailbox();
 525                 } else {
 526                     ASSERT(!m_destructionInProgress);
 527                     Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 528                 }
 529             }
 530             // Trigger Canvas2DLayerBridge self-destruction if this is the
 531             // last live mailbox and the layer bridge is not externally
 532             // referenced.
 533             mailboxInfo->m_parentLayerBridge.clear();
 534             return;
 535         }
 536     }
 537 }
 538
 539 WebLayer* Canvas2DLayerBridge::layer() const
 540 {
 541     ASSERT(!m_destructionInProgress);
 542     ASSERT(m_layer);
 543     return m_layer->layer();
 544 }
 545
 546 void Canvas2DLayerBridge::finalizeFrame()
 547 {
 548     ASSERT(!m_destructionInProgress);
 549     Canvas2DLayerManager::get().layerDidDraw(this);
 550     m_didRecordDrawCommand = true;
 551 }
 552
 553 Platform3DObject Canvas2DLayerBridge::getBackingTexture()
 554 {
 555     ASSERT(!m_destructionInProgress);
 556     if (!checkSurfaceValid())
 557         return 0;
 558     m_canvas->flush();
 559     context()->flush();
 560     GrRenderTarget* renderTarget = m_canvas->getTopDevice()->accessRenderTarget();
 561     if (renderTarget) {
 562         return renderTarget->asTexture()->getTextureHandle();
 563     }
 564     return 0;
 565 }
 566
 567 Canvas2DLayerBridge::MailboxInfo::MailboxInfo(const MailboxInfo& other) {
 568     // This copy constructor should only be used for Vector reallocation
 569     // Assuming 'other' is to be destroyed, we transfer m_image ownership
 570     // rather than do a refcount dance.
 571     memcpy(&m_mailbox, &other.m_mailbox, sizeof(m_mailbox));
 572     m_image = const_cast<MailboxInfo*>(&other)->m_image.release();
 573     m_status = other.m_status;
 574 }
 575
 576 } // namespace blink