Fixing Canvas2DLayerBridge to handle lost graphics contexts

Source/WebKit/chromium/tests/Canvas2DLayerBridgeTest.cpp

Index: Source/WebKit/chromium/tests/Canvas2DLayerBridgeTest.cpp
diff --git a/Source/WebKit/chromium/tests/Canvas2DLayerBridgeTest.cpp b/Source/WebKit/chromium/tests/Canvas2DLayerBridgeTest.cpp
index b1cc9829d8cb2f6f82c428037fa4da0cf8d375dc..ab039a43ccc1c411815a395d32e26f873033de9b 100644
--- a/Source/WebKit/chromium/tests/Canvas2DLayerBridgeTest.cpp
+++ b/Source/WebKit/chromium/tests/Canvas2DLayerBridgeTest.cpp
@@ -58,6 +58,33 @@ public:
     MOCK_METHOD3(appendCopy, void(unsigned, unsigned, WebSize));
 };
 
+class FakeCanvas2DLayerBridge : public Canvas2DLayerBridge {
+public:
+    static PassOwnPtr<FakeCanvas2DLayerBridge> create(PassRefPtr<GraphicsContext3D> context, SkDeferredCanvas* canvas, OpacityMode opacityMode, ThreadMode threadMode)
+    {
+        return adoptPtr(new FakeCanvas2DLayerBridge(context, canvas, opacityMode, threadMode));
+    }
+
+    void setFakeSharedContext(PassRefPtr<GraphicsContext3D> context)
+    {
+        m_fakeSharedContext = context;
+    }
+protected:
+    virtual PassRefPtr<GraphicsContext3D> getSharedContext() const OVERRIDE
+    {
+        return m_fakeSharedContext;
+    }
+
+    FakeCanvas2DLayerBridge(PassRefPtr<GraphicsContext3D> context, SkDeferredCanvas* canvas, OpacityMode opacityMode, ThreadMode threadMode) :
+        Canvas2DLayerBridge(context, canvas)
+    {
+        m_fakeSharedContext = m_context;
+        init(opacityMode, threadMode);
+    }
+
+    RefPtr<GraphicsContext3D> m_fakeSharedContext;
+};
+
 } // namespace
 
 class Canvas2DLayerBridgeTest : public Test {
@@ -75,7 +102,7 @@ protected:
 
         ::testing::Mock::VerifyAndClearExpectations(&mainMock);
 
-        OwnPtr<Canvas2DLayerBridge> bridge = Canvas2DLayerBridge::create(mainContext.release(), &canvas, Canvas2DLayerBridge::NonOpaque, threadMode);
+        OwnPtr<Canvas2DLayerBridge> bridge = FakeCanvas2DLayerBridge::create(mainContext.release(), &canvas, Canvas2DLayerBridge::NonOpaque, threadMode);
 
         ::testing::Mock::VerifyAndClearExpectations(&mainMock);
 
@@ -90,6 +117,37 @@ protected:
         ::testing::Mock::VerifyAndClearExpectations(&mainMock);
         ::testing::Mock::VerifyAndClearExpectations(&updater);
     }
+
+    void contextLostTest()

[Stephen White, 2013/05/31 15:06:18]

Thanks for the new test!

+    {
+        // This test fakes a context loss by substituting the shared context for a new,
+        // Which simulated what happens when the shared context successfully recoveres

[Stephen White, 2013/05/31 15:06:18]

Nit: "for a new, Which simulated what happens" i can haz grammar?

+        // after a lost context.
+        RefPtr<GraphicsContext3D> mainContext = GraphicsContext3D::createGraphicsContextFromWebContext(adoptPtr(new MockCanvasContext));
+        MockCanvasContext& mainMock = *static_cast<MockCanvasContext*>(mainContext->webContext());
+
+        RefPtr<GraphicsContext3D> substituteContext = GraphicsContext3D::createGraphicsContextFromWebContext(adoptPtr(new MockCanvasContext));
+        MockCanvasContext& substituteMock = *static_cast<MockCanvasContext*>(mainContext->webContext());
+
+        MockWebTextureUpdater updater;
+
+        SkDevice device(SkBitmap::kARGB_8888_Config, 300, 150);
+        SkDeferredCanvas canvas(&device);
+        OwnPtr<FakeCanvas2DLayerBridge> bridge = FakeCanvas2DLayerBridge::create(mainContext, &canvas, Canvas2DLayerBridge::NonOpaque, Canvas2DLayerBridge::SingleThread);
+
+        EXPECT_TRUE(bridge->m_context == mainContext);
+        bridge->prepareForDraw();
+        EXPECT_TRUE(bridge->m_context == mainContext);
+
+        bridge->setFakeSharedContext(substituteContext); // installing an alternat
+        bridge->prepareForDraw();
+        // m_context set to 0 shows that bridge detected lost context and attempted
+        // to recover. Recovery aborts because the fake context does not provide a grContext.
+        EXPECT_EQ(bridge->m_context.get(), (WebCore::GraphicsContext3D*)0);
+
+        ::testing::Mock::VerifyAndClearExpectations(&mainMock);
+        ::testing::Mock::VerifyAndClearExpectations(&substituteMock);
+    }
 };
 
 namespace {
@@ -104,4 +162,9 @@ TEST_F(Canvas2DLayerBridgeTest, testFullLifecycleThreaded)
     fullLifecycleTest(Canvas2DLayerBridge::Threaded);
 }
 
+TEST_F(Canvas2DLayerBridgeTest, testContextLost)
+{
+    contextLostTest();
+}
+
 } // namespace