Switch canvas.toBlob from idle-periods implementation to threaded implementation to allow experimen…

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

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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.
@@ skipping 543 matching lines @@
 
     String encodingMimeType = toEncodingMimeType(mimeType);
 
     ImageData* imageData = toImageData(BackBuffer);
     // imageData unref its data, which we still keep alive for the async toBlob thread
     ScopedDisposal<ImageData> disposer(imageData);
     // Add a ref to keep image data alive until completion of encoding
     RefPtr<DOMUint8ClampedArray> imageDataRef(imageData->data());
 
     RefPtr<CanvasAsyncBlobCreator> asyncCreatorRef = CanvasAsyncBlobCreator::create(imageDataRef.release(), encodingMimeType, imageData->size(), callback);
-    if (Platform::current()->isThreadedCompositingEnabled() && (encodingMimeType == DefaultMimeType)) {
-        asyncCreatorRef->scheduleAsyncBlobCreation(true);
-    } else {
-        asyncCreatorRef->scheduleAsyncBlobCreation(false, quality);
-    }
+
+    // TODO(xlai): Remove idle-periods version of implementation completely, http://crbug.com/564218
+    asyncCreatorRef->scheduleAsyncBlobCreation(false, quality);
 }
 
 SecurityOrigin* HTMLCanvasElement::securityOrigin() const
 {
     return document().securityOrigin();
 }
 
 bool HTMLCanvasElement::originClean() const
 {
     if (document().settings() && document().settings()->disableReadingFromCanvas())
@@ skipping 373 matching lines @@
     }
     return ImageBitmapSource::fulfillImageBitmap(scriptState, isPaintable() ? ImageBitmap::create(this, IntRect(sx, sy, sw, sh)) : nullptr);
 }
 
 bool HTMLCanvasElement::isOpaque() const
 {
     return m_context && !m_context->hasAlpha();
 }
 
 } // blink