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

Source/platform/graphics/gpu/DrawingBuffer.cpp

Index: Source/platform/graphics/gpu/DrawingBuffer.cpp
diff --git a/Source/platform/graphics/gpu/DrawingBuffer.cpp b/Source/platform/graphics/gpu/DrawingBuffer.cpp
index 0ec4bf9179012c1217b92aa3362f4f7d02e1e9df..dfb2056ba6cb307076c70f302e01a21bb9195c14 100644
--- a/Source/platform/graphics/gpu/DrawingBuffer.cpp
+++ b/Source/platform/graphics/gpu/DrawingBuffer.cpp
@@ -276,9 +276,9 @@ bool DrawingBuffer::prepareMailbox(blink::WebExternalTextureMailbox* outMailbox,
     return true;
 }
 
-void DrawingBuffer::mailboxReleased(const blink::WebExternalTextureMailbox& mailbox)
+void DrawingBuffer::mailboxReleased(const blink::WebExternalTextureMailbox& mailbox, bool lostResource)
 {
-    if (m_destructionInProgress) {
+    if (m_destructionInProgress || m_context->isContextLost() || lostResource) {

[Hongbo Min, 2014/07/08 09:56:38]

dshwang@, does it cover the cases you mentioned?

[dshwang, 2014/07/08 12:26:40]

yes, it covers all. thanks.

         mailboxReleasedWhileDestructionInProgress(mailbox);
         return;
     }
@@ -354,6 +354,7 @@ void DrawingBuffer::deleteMailbox(const blink::WebExternalTextureMailbox& mailbo
             deleteChromiumImageForTexture(&m_textureMailboxes[i]->textureInfo);
 
             m_context->deleteTexture(m_textureMailboxes[i]->textureInfo.textureId);
+            m_textureMailboxes[i]->m_parentDrawingBuffer.clear();

[dshwang, 2014/07/08 12:26:40]

this line is not necessary. do you add it to clarify?

[Hongbo Min, 2014/07/08 14:19:35]

It ensures the reference to DrawingBuffer is definitely cleared before it is
removed from the list.

[dshwang, 2014/07/08 15:07:05]

It's not important part but I want to ask why?
On removing it from the list, the destructor of DrawingBuffer is called, so
m_parentDrawingBuffer is cleared automatically.

[Hongbo Min, 2014/07/09 01:43:09]

Since each element in the list is ref-counted object, it is possible that the
mailbox is also referenced by others. Here I just want to ensure the
DrawingBuffer is definitely dereferenced before removing the mailbox.

             m_textureMailboxes.remove(i);
             return;
         }