Let canvas decide how to handle the case of resource lost reported by client: 2D part

Source/platform/graphics/Canvas2DLayerBridge.cpp

Index: Source/platform/graphics/Canvas2DLayerBridge.cpp
diff --git a/Source/platform/graphics/Canvas2DLayerBridge.cpp b/Source/platform/graphics/Canvas2DLayerBridge.cpp
index 5e2f83c293a99350ea6c8b818abf25026147f5bf..98fe6a9530fe14b8c1881fd36c54f63510c8ef24 100644
--- a/Source/platform/graphics/Canvas2DLayerBridge.cpp
+++ b/Source/platform/graphics/Canvas2DLayerBridge.cpp
@@ -489,28 +489,39 @@ Canvas2DLayerBridge::MailboxInfo* Canvas2DLayerBridge::createMailboxInfo() {
     return mailboxInfo;
 }
 
-void Canvas2DLayerBridge::mailboxReleased(const blink::WebExternalTextureMailbox& mailbox)
+void Canvas2DLayerBridge::mailboxReleased(const blink::WebExternalTextureMailbox& mailbox, bool lostResource)
 {
     freeReleasedMailbox(); // Never have more than one mailbox in the released state.
+    bool contextLost = m_contextProvider->context3d()->isContextLost() || !m_isSurfaceValid;
+    bool reallyLostResource = lostResource && contextLost;
     Vector<MailboxInfo>::iterator mailboxInfo;
     for (mailboxInfo = m_mailboxes.begin(); mailboxInfo < m_mailboxes.end(); ++mailboxInfo) {
         if (nameEquals(mailboxInfo->m_mailbox, mailbox)) {
             mailboxInfo->m_mailbox.syncPoint = mailbox.syncPoint;
             ASSERT(mailboxInfo->m_status == MailboxInUse);
-            mailboxInfo->m_status = MailboxReleased;
             // 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);
-            }
             ASSERT(mailboxInfo->m_parentLayerBridge.get() == this);
             mailboxInfo->m_parentLayerBridge.clear();
+
+            if (reallyLostResource) {
+                // No need to clean up the mailbox resource, but make sure the
+                // mailbox can also be reusable once the context is restored.
+                mailboxInfo->m_status = MailboxAvailable;
+                m_releasedMailboxInfoIndex = InvalidMailboxIndex;
+                Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
+            } else {
+                mailboxInfo->m_status = MailboxReleased;
+                m_releasedMailboxInfoIndex = mailboxInfo - m_mailboxes.begin();
+                m_framesSinceMailboxRelease = 0;
+                if (isHidden()) {
+                    freeReleasedMailbox();
+                } else {
+                    ASSERT(!m_destructionInProgress);
+                    Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
+                }
+            }
             return;
         }
     }