Enable GPU acceleration in 2D OffscreenCanvases on main thread

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 748 matching lines @@
 }
 
 bool HTMLCanvasElement::shouldAccelerate(const IntSize& size) const
 {
     if (m_context && !m_context->is2d())
         return false;
 
     if (RuntimeEnabledFeatures::forceDisplayList2dCanvasEnabled())
         return false;
 
-    Settings* settings = document().settings();
-    if (!settings || !settings->accelerated2dCanvasEnabled())
+    if (!RuntimeEnabledFeatures::accelerated2dCanvasEnabled())
         return false;
 
     int canvasPixelCount = size.width() * size.height();
 
     if (RuntimeEnabledFeatures::displayList2dCanvasEnabled()) {
 #if 0
         // TODO(junov): re-enable this code once we solve the problem of recording
         // GPU-backed images to an SkPicture for cross-context rendering crbug.com/490328
 
         // If the compositor provides GPU acceleration to display list canvases, we
         // prefer that over direct acceleration.
         if (document().viewportDescription().matchesHeuristicsForGpuRasterization())
             return false;
 #endif
         // If the GPU resources would be very expensive, prefer a display list.
         if (canvasPixelCount > ExpensiveCanvasHeuristicParameters::PreferDisplayListOverGpuSizeThreshold)
             return false;
     }
 
     // Do not use acceleration for small canvas.
-    if (canvasPixelCount < settings->minimumAccelerated2dCanvasSize())
+    Settings* settings = document().settings();
+    if (!settings || canvasPixelCount < settings->minimumAccelerated2dCanvasSize())
         return false;
 
     if (!Platform::current()->canAccelerate2dCanvas())
         return false;
 
     // When GPU allocated memory runs low (due to having created too many
     // accelerated canvases), the compositor starves and browser becomes laggy.
     // Thus, we should stop allocating more GPU memory to new canvases created
     // when the current memory usage exceeds the threshold.
     if (ImageBuffer::getGlobalGPUMemoryUsage() >= MaxGlobalGPUMemoryUsage)
@@ skipping 426 matching lines @@
 
 bool HTMLCanvasElement::createSurfaceLayer()
 {
     DCHECK(!m_surfaceLayerBridge);
     std::unique_ptr<CanvasSurfaceLayerBridgeClient> bridgeClient = wrapUnique(new CanvasSurfaceLayerBridgeClientImpl());
     m_surfaceLayerBridge = wrapUnique(new CanvasSurfaceLayerBridge(std::move(bridgeClient)));
     return m_surfaceLayerBridge->createSurfaceLayer(this->width(), this->height());
 }
 
 } // namespace blink