Fixes a bug when the framebuffer is cleared with invalid scissor rect

cc/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/gl_renderer.h"
 
 #include "cc/compositor_frame_metadata.h"
 #include "cc/draw_quad.h"
 #include "cc/prioritized_resource_manager.h"
 #include "cc/resource_provider.h"
@@ skipping 101 matching lines @@
     FakeRendererGL(RendererClient* client, OutputSurface* outputSurface, ResourceProvider* resourceProvider) : GLRenderer(client, outputSurface, resourceProvider) { }
 
     // GLRenderer methods.
 
     // Changing visibility to public.
     using GLRenderer::initialize;
     using GLRenderer::isBackbufferDiscarded;
     using GLRenderer::drawQuad;
     using GLRenderer::beginDrawingFrame;
     using GLRenderer::finishDrawingQuadList;
+
+    void clearFramebuffer(DrawingFrame& frame) {
+      // Check that scissor test is disabled unless we're using scissor
+      // as optimization when usingPartialSwap is on.
+      if (!capabilities().usingPartialSwap)
+          EXPECT_FALSE(isScissorEnabledForTesting());

[danakj, 2013/01/29 00:00:46]

Do we have any unit tests that would fail this without your changes in
direct_renderer.cc? Which one(s)?

+      GLRenderer::clearFramebuffer(frame);
+    }
 };
 
 class GLRendererTest : public testing::Test {
 protected:
     GLRendererTest()
         : m_suggestHaveBackbufferYes(1, true)
         , m_suggestHaveBackbufferNo(1, false)
         , m_outputSurface(FakeOutputSurface::Create3d(scoped_ptr<WebKit::WebGraphicsContext3D>(new FrameCountingMemoryAllocationSettingContext())))
         , m_resourceProvider(ResourceProvider::create(m_outputSurface.get()))
         , m_renderer(&m_mockClient, m_outputSurface.get(), m_resourceProvider.get())
@@ skipping 499 matching lines @@
 
     renderer.decideRenderPassAllocationsForFrame(mockClient.renderPassesInDrawOrder());
     renderer.drawFrame(mockClient.renderPassesInDrawOrder());
 
     // In multiple render passes all but the root pass should clear the framebuffer.
     Mock::VerifyAndClearExpectations(&mockContext);
 }
 
 }  // namespace
 }  // namespace cc