Fix scrollbars missing after lost context

cc/scrollbar_layer_unittest.cc

Index: cc/scrollbar_layer_unittest.cc
diff --git a/cc/scrollbar_layer_unittest.cc b/cc/scrollbar_layer_unittest.cc
index e6a7bff0b3067757693a358b602684fbf7b6c92b..b9be950f15b6473ab3b951c67d6c0285e5bdc955 100644
--- a/cc/scrollbar_layer_unittest.cc
+++ b/cc/scrollbar_layer_unittest.cc
@@ -9,12 +9,14 @@
 #include "cc/single_thread_proxy.h"
 #include "cc/test/fake_impl_proxy.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
+#include "cc/test/fake_scrollbar_layer.h"
 #include "cc/test/fake_scrollbar_theme_painter.h"
 #include "cc/test/fake_web_graphics_context_3d.h"
 #include "cc/test/fake_web_scrollbar.h"
 #include "cc/test/fake_web_scrollbar_theme_geometry.h"
 #include "cc/test/layer_tree_test_common.h"
 #include "cc/tree_synchronizer.h"
+#include "gpu/GLES2/gl2extchromium.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebScrollbar.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebScrollbarThemeGeometry.h"
@@ -194,5 +196,71 @@ TEST_F(ScrollbarLayerTestMaxTextureSize, runTest) {
     runTest(true);
 }
 
+class ScrollbarLayerLostContext : public ThreadedTest {

[danakj, 2013/01/18 05:07:49]

Can you stick this in layer_tree_host_unittest_context.cc with the other
lost-context tests?

then you can reuse some machinery there like LoseContext() and
createOutputSurface()

[piman, 2013/01/18 23:10:08]

Done.

+public:
+    ScrollbarLayerLostContext() : m_commits(0), m_context(NULL) {}
+
+    virtual void beginTest() OVERRIDE
+    {
+        m_layerTreeHost->initializeRendererIfNeeded();

[danakj, 2013/01/18 05:07:49]

this should be done by base classes already, shouldn't need it.

[piman, 2013/01/18 23:10:08]

Done.

+
+        m_scrollLayer = Layer::create();
+        m_scrollbarLayer = FakeScrollbarLayer::Create(false, true, m_scrollLayer->id());
+        m_scrollbarLayer->setBounds(gfx::Size(10, 100));
+        m_layerTreeHost->rootLayer()->addChild(m_scrollbarLayer);
+        m_layerTreeHost->rootLayer()->addChild(m_scrollLayer);
+        postSetNeedsCommitToMainThread();
+    }
+
+    virtual void afterTest() OVERRIDE
+    {
+    }
+
+    virtual void commitCompleteOnThread(LayerTreeHostImpl* impl) OVERRIDE
+    {
+        ++m_commits;
+        switch(m_commits) {
+        case 1:
+            // First (regular) update, we should upload 2 resources (thumb, and
+            // backtrack).
+            EXPECT_EQ(1, m_scrollbarLayer->update_count());
+            EXPECT_EQ(0, m_scrollbarLayer->last_update_full_upload_size());
+            EXPECT_EQ(2, m_scrollbarLayer->last_update_partial_upload_size());
+            loseContext();
+            break;
+        case 2:
+            // Second update, after the lost context, we should still upload 2
+            // resources even if the contents haven't changed.
+            EXPECT_EQ(2, m_scrollbarLayer->update_count());
+            EXPECT_EQ(0, m_scrollbarLayer->last_update_full_upload_size());
+            EXPECT_EQ(2, m_scrollbarLayer->last_update_partial_upload_size());
+            endTest();
+            break;
+        }
+    }
+
+    virtual scoped_ptr<OutputSurface> createOutputSurface() OVERRIDE {
+        DCHECK(!m_context);
+        scoped_ptr<OutputSurface> outputSurface = TestHooks::createOutputSurface();
+        m_context = outputSurface->Context3D();
+        return outputSurface.Pass();
+    }
+
+private:
+    void loseContext() {
+        DCHECK(m_context);
+        m_context->loseContextCHROMIUM(GL_GUILTY_CONTEXT_RESET_ARB,
+                                       GL_INNOCENT_CONTEXT_RESET_ARB);
+        m_context = NULL;
+    }
+
+    int m_commits;
+    WebKit::WebGraphicsContext3D* m_context;
+    scoped_refptr<FakeScrollbarLayer> m_scrollbarLayer;
+    scoped_refptr<Layer> m_scrollLayer;
+};
+
+SINGLE_AND_MULTI_THREAD_TEST_F(ScrollbarLayerLostContext)
+
 }  // namespace
 }  // namespace cc