NOT FOR COMMIT: sample CL to debug white flashes.

third_party/WebKit/Source/web/WebViewImpl.cpp

Index: third_party/WebKit/Source/web/WebViewImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebViewImpl.cpp b/third_party/WebKit/Source/web/WebViewImpl.cpp
index 107878abf2a9750ffbc8f1fbdcf4cac5e29e5b78..108bba42dda9eba09dacdb3359883d990df4db66 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.cpp
+++ b/third_party/WebKit/Source/web/WebViewImpl.cpp
@@ -4204,6 +4204,7 @@ void WebViewImpl::setRootGraphicsLayer(GraphicsLayer* layer)
         // This means that we're transitioning to a new page. Suppress
         // commits until Blink generates invalidations so we don't
         // attempt to paint too early in the next page load.
+        LOG(ERROR) << "Stop painting";
         m_layerTreeView->setDeferCommits(true);
         m_layerTreeView->clearRootLayer();
         visualViewport.clearLayersForTreeView(m_layerTreeView);
@@ -4510,6 +4511,7 @@ void WebViewImpl::detachPaintArtifactCompositor()
     if (!m_layerTreeView)
         return;
 
+    LOG(ERROR) << "Stop painting";
     m_layerTreeView->setDeferCommits(true);
     m_layerTreeView->clearRootLayer();
 }