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

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

Index: third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DTest.cpp
diff --git a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DTest.cpp b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DTest.cpp
index c8c3ba5f08bf0582f08dba571b32d7dfb8472587..c820db7988a6f51a4e8f94c01fdf76bca3935e42 100644
--- a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DTest.cpp
+++ b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DTest.cpp
@@ -999,10 +999,24 @@ TEST_F(CanvasRenderingContext2DTest, GetImageDataDisablesAcceleration) {
   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());