cc: Invalidate framebuffer contents when clearing

cc/output/gl_renderer_unittest.cc

 // Copyright 2012 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 "cc/output/gl_renderer.h"
 
 #include <set>
 
 #include "cc/base/math_util.h"
 #include "cc/debug/test_web_graphics_context_3d.h"
@@ skipping 681 matching lines @@
 
   FakeRendererClient renderer_client;
   FakeRendererGL renderer(
       &renderer_client, output_surface.get(), resource_provider.get());
 
   renderer.Initialize();
 }
 
 class ClearCountingContext : public TestWebGraphicsContext3D {
  public:
-  ClearCountingContext() : clear_(0) {}
+  ClearCountingContext() {
+    test_capabilities_.discard_framebuffer = true;
+  }
 
-  virtual void clear(WGC3Dbitfield) { clear_++; }
-
-  int clear_count() const { return clear_; }
-
- private:
-  int clear_;
+  MOCK_METHOD3(discardFramebufferEXT,
+               void(WGC3Denum target,
+                    WGC3Dsizei numAttachments,
+                    const WGC3Denum* attachments));
+  MOCK_METHOD1(clear, void(WGC3Dbitfield mask));
 };
 
 TEST(GLRendererTest2, OpaqueBackground) {
   scoped_ptr<ClearCountingContext> context_owned(new ClearCountingContext);
   ClearCountingContext* context = context_owned.get();
 
   FakeOutputSurfaceClient output_surface_client;
   scoped_ptr<OutputSurface> output_surface(FakeOutputSurface::Create3d(
       context_owned.PassAs<TestWebGraphicsContext3D>()));
   CHECK(output_surface->BindToClient(&output_surface_client));
 
   scoped_ptr<ResourceProvider> resource_provider(
       ResourceProvider::Create(output_surface.get(), 0));
 
   FakeRendererClient renderer_client;
   FakeRendererGL renderer(
       &renderer_client, output_surface.get(), resource_provider.get());
 
   renderer_client.root_render_pass()->has_transparent_background = false;
 
   EXPECT_TRUE(renderer.Initialize());
 
-  renderer.DrawFrame(renderer_client.render_passes_in_draw_order(), NULL);
-
 // On DEBUG builds, render passes with opaque background clear to blue to
 // easily see regions that were not drawn on the screen.
+  EXPECT_CALL(*context, discardFramebufferEXT(GL_FRAMEBUFFER, 1, _))
+      .Times(1);
 #ifdef NDEBUG
-  EXPECT_EQ(0, context->clear_count());
+  EXPECT_CALL(*context, clear(_)).Times(0);
 #else
-  EXPECT_EQ(1, context->clear_count());
+  EXPECT_CALL(*context, clear(_)).Times(1);
 #endif
+  renderer.DrawFrame(renderer_client.render_passes_in_draw_order(), NULL);
+  Mock::VerifyAndClearExpectations(context);
 }
 
 TEST(GLRendererTest2, TransparentBackground) {
   scoped_ptr<ClearCountingContext> context_owned(new ClearCountingContext);
   ClearCountingContext* context = context_owned.get();
 
   FakeOutputSurfaceClient output_surface_client;
   scoped_ptr<OutputSurface> output_surface(FakeOutputSurface::Create3d(
       context_owned.PassAs<TestWebGraphicsContext3D>()));
   CHECK(output_surface->BindToClient(&output_surface_client));
 
   scoped_ptr<ResourceProvider> resource_provider(
       ResourceProvider::Create(output_surface.get(), 0));
 
   FakeRendererClient renderer_client;
   FakeRendererGL renderer(
       &renderer_client, output_surface.get(), resource_provider.get());
 
   renderer_client.root_render_pass()->has_transparent_background = true;
 
   EXPECT_TRUE(renderer.Initialize());
 
+  EXPECT_CALL(*context, discardFramebufferEXT(GL_FRAMEBUFFER, 1, _))
+      .Times(1);
+  EXPECT_CALL(*context, clear(_)).Times(1);
   renderer.DrawFrame(renderer_client.render_passes_in_draw_order(), NULL);
 
-  EXPECT_EQ(1, context->clear_count());
+  Mock::VerifyAndClearExpectations(context);
 }
 
 class VisibilityChangeIsLastCallTrackingContext
     : public TestWebGraphicsContext3D {
  public:
   VisibilityChangeIsLastCallTrackingContext()
       : last_call_was_set_visibility_(false) {
     test_capabilities_.set_visibility = true;
     test_capabilities_.discard_backbuffer = true;
   }
@@ skipping 848 matching lines @@
   base::MessageLoop::current()->Run();
 
   // The sync point should have happened.
   EXPECT_EQ(1, sync_point_callback_count);
   EXPECT_EQ(1, other_callback_count);
 }
 #endif  // OS_ANDROID
 
 }  // namespace
 }  // namespace cc