Work around unknown Mac Intel driver bug causing non-deterministic behavior in GPU readback from 2D

third_party/WebKit/Source/web/WebSettingsImpl.cpp

 /*
  * Copyright (C) 2009 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 480 matching lines @@
 }
 
 void WebSettingsImpl::setAccelerated2dCanvasMSAASampleCount(int count) {
   m_settings->setAccelerated2dCanvasMSAASampleCount(count);
 }
 
 void WebSettingsImpl::setAntialiased2dCanvasEnabled(bool enabled) {
   m_settings->setAntialiased2dCanvasEnabled(enabled);
 }
 
+void WebSettingsImpl::setForceSoftwareReadbackFrom2DCanvas(bool enabled) {
+  m_settings->setForceSoftwareReadbackFrom2DCanvas(enabled);
+}
+
 void WebSettingsImpl::setAntialiasedClips2dCanvasEnabled(bool enabled) {
   m_settings->setAntialiasedClips2dCanvasEnabled(enabled);
 }
 
 void WebSettingsImpl::setPreferCompositingToLCDTextEnabled(bool enabled) {
   m_devToolsEmulator->setPreferCompositingToLCDTextEnabled(enabled);
 }
 
 void WebSettingsImpl::setMinimumAccelerated2dCanvasSize(int numPixels) {
   m_settings->setMinimumAccelerated2dCanvasSize(numPixels);
@@ skipping 197 matching lines @@
 void WebSettingsImpl::setExpensiveBackgroundThrottlingMaxBudget(
     float maxBudget) {
   m_expensiveBackgroundThrottlingMaxBudget = maxBudget;
 }
 
 void WebSettingsImpl::setExpensiveBackgroundThrottlingMaxDelay(float maxDelay) {
   m_expensiveBackgroundThrottlingMaxDelay = maxDelay;
 }
 
 }  // namespace blink