PrepareMailbox when all mailboxes have been returned

Source/platform/graphics/Canvas2DLayerBridge.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 75 matching lines @@
     , m_surfaceIsValid(true)
     , m_framesPending(0)
     , m_framesSinceMailboxRelease(0)
     , m_destructionInProgress(false)
     , m_rateLimitingEnabled(false)
     , m_isHidden(false)
     , m_next(0)
     , m_prev(0)
     , m_lastImageId(0)
     , m_releasedMailboxInfoIndex(InvalidMailboxIndex)
+    , m_activeMailboxCount(0)
 {
     ASSERT(m_canvas);
     ASSERT(m_contextProvider);
     // Used by browser tests to detect the use of a Canvas2DLayerBridge.
     TRACE_EVENT_INSTANT0("test_gpu", "Canvas2DLayerBridgeCreation");
     m_layer = adoptPtr(blink::Platform::current()->compositorSupport()->createExternalTextureLayer(this));
     m_layer->setOpaque(opacityMode == Opaque);
     m_layer->setBlendBackgroundColor(opacityMode != Opaque);
     GraphicsLayer::registerContentsLayer(m_layer->layer());
     m_layer->setRateLimitContext(m_rateLimitingEnabled);
@@ skipping 256 matching lines @@
     RefPtr<SkImage> image = adoptRef(m_canvas->newImageSnapshot());
 
     // Early exit if canvas was not drawn to since last prepareMailbox
     if (image->uniqueID() == m_lastImageId)
         return false;
     m_lastImageId = image->uniqueID();
 
     MailboxInfo* mailboxInfo = createMailboxInfo();
     mailboxInfo->m_status = MailboxInUse;
     mailboxInfo->m_image = image;
+    m_activeMailboxCount++;
 
     // Because of texture sharing with the compositor, we must invalidate
     // the state cached in skia so that the deferred copy on write
     // in SkSurface_Gpu does not make any false assumptions.
     mailboxInfo->m_image->getTexture()->invalidateCachedState();
 
     ASSERT(mailboxInfo->m_mailbox.syncPoint == 0);
     ASSERT(mailboxInfo->m_image.get());
     ASSERT(mailboxInfo->m_image->getTexture());
 
@@ skipping 50 matching lines @@
 
 void Canvas2DLayerBridge::mailboxReleased(const blink::WebExternalTextureMailbox& mailbox)
 {
     freeReleasedMailbox(); // Never have more than one mailbox in the released state.
     Vector<MailboxInfo>::iterator mailboxInfo;
     for (mailboxInfo = m_mailboxes.begin(); mailboxInfo < m_mailboxes.end(); ++mailboxInfo) {
         if (!memcmp(mailboxInfo->m_mailbox.name, mailbox.name, sizeof(mailbox.name))) {
             mailboxInfo->m_mailbox.syncPoint = mailbox.syncPoint;
             ASSERT(mailboxInfo->m_status == MailboxInUse);
             mailboxInfo->m_status = MailboxReleased;
+            ASSERT(m_activeMailboxCount > 0);
+            if (!--m_activeMailboxCount)
+                m_lastImageId = 0;
             // Trigger Canvas2DLayerBridge self-destruction if this is the
             // last live mailbox and the layer bridge is not externally
             // referenced.
             m_releasedMailboxInfoIndex = mailboxInfo - m_mailboxes.begin();
             m_framesSinceMailboxRelease = 0;
             if (isHidden()) {
                 freeReleasedMailbox();
             } else {
                 ASSERT(!m_destructionInProgress);
                 Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
@@ skipping 36 matching lines @@
 Canvas2DLayerBridge::MailboxInfo::MailboxInfo(const MailboxInfo& other) {
     // This copy constructor should only be used for Vector reallocation
     // Assuming 'other' is to be destroyed, we transfer m_image ownership
     // rather than do a refcount dance.
     memcpy(&m_mailbox, &other.m_mailbox, sizeof(m_mailbox));
     m_image = const_cast<MailboxInfo*>(&other)->m_image.release();
     m_status = other.m_status;
 }
 
 }