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

cc/gl_renderer_unittest.cc

Index: cc/gl_renderer_unittest.cc
diff --git a/cc/gl_renderer_unittest.cc b/cc/gl_renderer_unittest.cc
index 89603b1ece65c8fc80ad1e4ae92a6678a0ed091f..5ca2e35bc7371f19718b9cd84d364911ff7ad3ba 100644
--- a/cc/gl_renderer_unittest.cc
+++ b/cc/gl_renderer_unittest.cc
@@ -636,5 +636,56 @@ TEST(GLRendererTest2, shouldClearRootRenderPass)
     Mock::VerifyAndClearExpectations(&mockContext);
 }
 
+class ScissorTestOnClearCheckingContext : public FakeWebGraphicsContext3D {
+public:
+    ScissorTestOnClearCheckingContext() : m_scissorEnabled(false) { }
+
+    virtual void clear(WGC3Dbitfield)
+    {
+        EXPECT_FALSE(m_scissorEnabled);
+    }
+
+    virtual void enable(WGC3Denum cap)
+    {
+        if (cap == GL_SCISSOR_TEST)
+            m_scissorEnabled = true;
+    }
+
+    virtual void disable(WGC3Denum cap)
+    {
+        if (cap == GL_SCISSOR_TEST)
+            m_scissorEnabled = false;
+    }
+
+private:
+    bool m_scissorEnabled;
+};
+
+TEST(GLRendererTest2, scissorTestWhenClearing) {
+    FakeRendererClient mockClient;
+    scoped_ptr<OutputSurface> outputSurface(FakeOutputSurface::Create3d(scoped_ptr<WebKit::WebGraphicsContext3D>(new ScissorTestOnClearCheckingContext)));
+    scoped_ptr<ResourceProvider> resourceProvider(ResourceProvider::create(outputSurface.get()));
+    FakeRendererGL renderer(&mockClient, outputSurface.get(), resourceProvider.get());
+    EXPECT_TRUE(renderer.initialize());
+    renderer.enableScissorForTesting();

[danakj, 2013/01/29 21:39:20]

Instead of this, I think you could set a clip_rect and is_clipped=true on the
last quad in the child render pass. That would more mimic the real situation.

+
+    gfx::Rect viewportRect(mockClient.deviceViewportSize());
+    ScopedPtrVector<RenderPass>& renderPasses = mockClient.renderPassesInDrawOrder();
+    renderPasses.clear();
+
+    RenderPass::Id rootPassId(1, 0);
+    TestRenderPass* rootPass = addRenderPass(renderPasses, rootPassId, viewportRect, gfx::Transform());
+    addQuad(rootPass, viewportRect, SK_ColorGREEN);
+
+    RenderPass::Id childPassId(2, 0);
+    TestRenderPass* childPass = addRenderPass(renderPasses, childPassId, viewportRect, gfx::Transform());
+    addQuad(childPass, viewportRect, SK_ColorBLUE);
+
+    addRenderPassQuad(rootPass, childPass);
+
+    renderer.decideRenderPassAllocationsForFrame(mockClient.renderPassesInDrawOrder());
+    renderer.drawFrame(mockClient.renderPassesInDrawOrder());
+}
+
 }  // namespace
 }  // namespace cc