Make OffscreenCanvas commit() propagate the origin-clean flag.

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
index b90acddd296bc82cb1aae752286133a96ea39cef..65c4d7ab0e63357aa3f75deeba1c8a86ee762d4d 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -641,6 +641,7 @@ ImageData* HTMLCanvasElement::toImageData(SourceDrawingBuffer sourceBuffer,
   if (hasImageBuffer()) {
     snapshot = buffer()->newSkImageSnapshot(PreferNoAcceleration, reason);
   } else if (placeholderFrame()) {
+    DCHECK(placeholderFrame()->originClean());
     // TODO(ccameron): Canvas should produce sRGB images.
     // https://crbug.com/672299
     snapshot = placeholderFrame()->imageForCurrentFrame(
@@ -782,6 +783,8 @@ bool HTMLCanvasElement::originClean() const {
   if (document().settings() &&
       document().settings()->disableReadingFromCanvas())
     return false;
+  if (placeholderFrame())
+    return placeholderFrame()->originClean();
   return m_originClean;
 }