Reland of "Make disabling 2d canvas GPU acceleration for getImageData less aggressive."

third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/canvas2d/CanvasRenderingContext2D.h"
 
 #include <memory>
 #include "bindings/core/v8/V8BindingForTesting.h"
 #include "core/dom/Document.h"
 #include "core/frame/FrameView.h"
@@ skipping 981 matching lines @@
                  Canvas2DLayerBridge::EnableAcceleration);
   std::unique_ptr<Canvas2DImageBufferSurface> surface(
       new Canvas2DImageBufferSurface(bridge, size));
   canvasElement().createImageBufferUsingSurfaceForTesting(std::move(surface));
 
   EXPECT_TRUE(canvasElement().buffer()->isAccelerated());
   EXPECT_EQ(1u, getGlobalAcceleratedImageBufferCount());
   EXPECT_EQ(720000, getGlobalGPUMemoryUsage());
 
   DummyExceptionStateForTesting exceptionState;
+  for (int i = 0;
+       i <
+       ExpensiveCanvasHeuristicParameters::GPUReadbackMinSuccessiveFrames - 1;
+       i++) {
+    context2d()->getImageData(0, 0, 1, 1, exceptionState);
+    canvasElement().finalizeFrame();
+
+    EXPECT_FALSE(exceptionState.hadException());
+    EXPECT_TRUE(canvasElement().buffer()->isAccelerated());
+    EXPECT_EQ(1u, getGlobalAcceleratedImageBufferCount());
+    EXPECT_EQ(720000, getGlobalGPUMemoryUsage());
+  }
+
   context2d()->getImageData(0, 0, 1, 1, exceptionState);
+  canvasElement().finalizeFrame();
 
   EXPECT_FALSE(exceptionState.hadException());
-  if (ExpensiveCanvasHeuristicParameters::GetImageDataForcesNoAcceleration) {
+  if (ExpensiveCanvasHeuristicParameters::GPUReadbackForcesNoAcceleration) {
     EXPECT_FALSE(canvasElement().buffer()->isAccelerated());
     EXPECT_EQ(0u, getGlobalAcceleratedImageBufferCount());
     EXPECT_EQ(0, getGlobalGPUMemoryUsage());
   } else {
     EXPECT_TRUE(canvasElement().buffer()->isAccelerated());
     EXPECT_EQ(1u, getGlobalAcceleratedImageBufferCount());
     EXPECT_EQ(720000, getGlobalGPUMemoryUsage());
   }
 
   // Restore global state to prevent side-effects on other tests
@@ skipping 340 matching lines @@
 
   RuntimeEnabledFeatures::setExperimentalCanvasFeaturesEnabled(
       experimentalCanvasFeaturesRuntimeFlag);
   RuntimeEnabledFeatures::setColorCorrectRenderingEnabled(
       colorCorrectRenderingRuntimeFlag);
   RuntimeEnabledFeatures::setColorCorrectRenderingDefaultModeEnabled(
       colorCorrectRenderingDefaultModeRuntimeFlag);
 }
 
 }  // namespace blink