cc: Make async readback path use async glRreadPixels.

cc/test/pixel_test.cc

Index: cc/test/pixel_test.cc
diff --git a/cc/test/pixel_test.cc b/cc/test/pixel_test.cc
index 5976ae350db3ecc0af2c04beec660f975b531050..c645b0106f473b380ca46c89a0d61f4bcf589a99 100644
--- a/cc/test/pixel_test.cc
+++ b/cc/test/pixel_test.cc
@@ -4,6 +4,7 @@
 
 #include "cc/test/pixel_test.h"
 
+#include "base/message_loop.h"
 #include "base/path_service.h"
 #include "cc/output/compositor_frame_metadata.h"
 #include "cc/output/gl_renderer.h"
@@ -86,13 +87,16 @@ bool PixelTest::RunPixelTest(RenderPassList* pass_list,
   renderer_->DecideRenderPassAllocationsForFrame(*pass_list);
   renderer_->DrawFrame(pass_list);
 
-  // TODO(danakj): When the glReadPixels is async, wait for it to finish.
+  // Wait for the readback to complete.
+  output_surface_->context3d()->finish();
+  base::MessageLoop::current()->Run();

[piman, 2013/04/27 00:42:25]

Any way we can use base::RunLoop instead (generally safer)?

[danakj, 2013/04/29 14:59:05]

I will introduce myself to RunLoop. (Oh, it is neet.)

 
   return PixelsMatchReference(ref_file, comparator);
 }
 
 void PixelTest::ReadbackResult(scoped_ptr<SkBitmap> bitmap) {
   result_bitmap_ = bitmap.Pass();
+  base::MessageLoop::current()->QuitWhenIdle();
 }
 
 bool PixelTest::PixelsMatchReference(const base::FilePath& ref_file,