Merge 116587 - [chromium] Don't draw when canDraw() is false

Source/WebCore/platform/graphics/chromium/cc/CCLayerTreeHostImpl.cpp

 /*
  * Copyright (C) 2011 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
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 362 matching lines @@
     // TODO(aelias): Hardcoding the first child here is weird. Think of
     // a cleaner way to get the contentBounds on the Impl side.
     if (!m_scrollLayerImpl || m_scrollLayerImpl->children().isEmpty())
         return IntSize();
     return m_scrollLayerImpl->children()[0]->contentBounds();
 }
 
 bool CCLayerTreeHostImpl::prepareToDraw(FrameData& frame)
 {
     TRACE_EVENT("CCLayerTreeHostImpl::prepareToDraw", this, 0);
+    ASSERT(canDraw());
 
     frame.renderPasses.clear();
     frame.renderSurfaceLayerList.clear();
 
-    if (!m_rootLayerImpl)
-        return false;
-
     if (!calculateRenderPasses(frame.renderPasses, frame.renderSurfaceLayerList)) {
         // We're missing textures on an animating layer. Request a commit.
         m_client->setNeedsCommitOnImplThread();
         return false;
     }
 
     // If we return true, then we expect drawLayers() to be called before this function is called again.
     return true;
 }
 
 void CCLayerTreeHostImpl::setContentsMemoryAllocationLimitBytes(size_t bytes)
 {
     m_client->postSetContentsMemoryAllocationLimitBytesToMainThreadOnImplThread(bytes);
 }
 
 void CCLayerTreeHostImpl::drawLayers(const FrameData& frame)
 {
     TRACE_EVENT("CCLayerTreeHostImpl::drawLayers", this, 0);
-    ASSERT(m_layerRenderer);
-
-    if (!m_rootLayerImpl)
-        return;
+    ASSERT(canDraw());
 
     // FIXME: use the frame begin time from the overall compositor scheduler.
     // This value is currently inaccessible because it is up in Chromium's
     // RenderWidget.
 
     m_fpsCounter->markBeginningOfFrame(currentTime());
     m_layerRenderer->beginDrawingFrame(m_rootLayerImpl->renderSurface());
 
     for (size_t i = 0; i < frame.renderPasses.size(); ++i)
         m_layerRenderer->drawRenderPass(frame.renderPasses[i].get());
@@ skipping 487 matching lines @@
         return;
 
     bool isContinuing = m_activeGestureAnimation->animate(monotonicTime);
     if (isContinuing)
         m_client->setNeedsRedrawOnImplThread();
     else
         m_activeGestureAnimation.clear();
 }
 
 } // namespace WebCore