cc: Made image comparison for pixel tests error tolerant.

cc/gl_renderer_pixeltest.cc

Index: cc/gl_renderer_pixeltest.cc
diff --git a/cc/gl_renderer_pixeltest.cc b/cc/gl_renderer_pixeltest.cc
index 347428b690e0694a40d694c14b26100057ee9ace..52c3d0d5f07e40aa933ae9b04a2cb98907de1710 100644
--- a/cc/gl_renderer_pixeltest.cc
+++ b/cc/gl_renderer_pixeltest.cc
@@ -64,7 +64,8 @@ class GLRendererPixelTest : public testing::Test {
                                    resource_provider_.get());
   }
 
-  bool PixelsMatchReference(base::FilePath ref_file, gfx::Rect viewport_rect) {
+  bool PixelsMatchReference(base::FilePath ref_file, gfx::Rect viewport_rect,
+                            const PixelComparator& comparator) {
     SkBitmap bitmap;
     bitmap.setConfig(SkBitmap::kARGB_8888_Config,
                      viewport_rect.width(), viewport_rect.height());
@@ -76,7 +77,7 @@ class GLRendererPixelTest : public testing::Test {
     if (!PathService::Get(cc::DIR_TEST_DATA, &test_data_dir))
       return false;
 
-    return IsSameAsPNGFile(bitmap, test_data_dir.Append(ref_file));
+    return MatchesPNGFile(bitmap, test_data_dir.Append(ref_file), comparator);
   }
 
   scoped_ptr<OutputSurface> output_surface_;
@@ -152,7 +153,7 @@ TEST_F(GLRendererPixelTest, simpleGreenRect) {
 
   EXPECT_TRUE(PixelsMatchReference(
       base::FilePath(FILE_PATH_LITERAL("green.png")),
-      rect));
+      rect, ExactPixelComparator()));
 }
 
 TEST_F(GLRendererPixelTest, RenderPassChangesSize) {
@@ -195,7 +196,8 @@ TEST_F(GLRendererPixelTest, RenderPassChangesSize) {
   renderer_->drawFrame(pass_list);
 
   EXPECT_TRUE(PixelsMatchReference(
-      base::FilePath(FILE_PATH_LITERAL("blue_yellow.png")), viewport_rect));
+      base::FilePath(FILE_PATH_LITERAL("blue_yellow.png")), viewport_rect,
+      ExactPixelComparator()));
 }
 #endif