cc: Don't draw and swap if the frame will not change.

cc/trees/layer_tree_host_unittest.cc

Index: cc/trees/layer_tree_host_unittest.cc
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 5c9c2dac823a360b28e841f372a8465e3c394f74..3a5018e332c3d5bf0853ad02fc61a3e6db203c90 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -142,21 +142,23 @@ public:
 
     virtual void DrawLayersOnThread(LayerTreeHostImpl* impl) OVERRIDE
     {
-        if (impl->active_tree()->source_frame_number() == 0)
-            PostSetNeedsCommitToMainThread();
-        else if (impl->active_tree()->source_frame_number() == 1)
-            EndTest();
+        ++m_numDraws;
     }
 
-    virtual void CommitCompleteOnThread(LayerTreeHostImpl*) OVERRIDE
+    virtual void CommitCompleteOnThread(LayerTreeHostImpl* impl) OVERRIDE
     {
         m_numCommits++;
+
+        if (impl->active_tree()->source_frame_number() == 0)
+            PostSetNeedsCommitToMainThread();
+        else if (impl->active_tree()->source_frame_number() == 1)
+            EndTest();
     }
 
     virtual void AfterTest() OVERRIDE
     {
         EXPECT_EQ(2, m_numCommits);
-        EXPECT_GE(2, m_numDraws);
+        EXPECT_EQ(1, m_numDraws);
     }
 
 private:
@@ -840,7 +842,7 @@ public:
 
         // Compute all the layer transforms for the frame.
         LayerTreeHostImpl::FrameData frameData;
-        impl->PrepareToDraw(&frameData);
+        impl->PrepareToDraw(&frameData, gfx::Rect());
         impl->DidDrawAllLayers(frameData);
 
         const LayerTreeHostImpl::LayerList& renderSurfaceLayerList =
@@ -1288,11 +1290,11 @@ SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostTestCompositeAndReadbackCleanup)
 class LayerTreeHostTestSurfaceNotAllocatedForLayersOutsideMemoryLimit : public LayerTreeHostTest {
 public:
     LayerTreeHostTestSurfaceNotAllocatedForLayersOutsideMemoryLimit()
-        : m_rootLayer(ContentLayerWithUpdateTracking::Create(&m_fakeDelegate))
-        , m_surfaceLayer1(ContentLayerWithUpdateTracking::Create(&m_fakeDelegate))
-        , m_replicaLayer1(ContentLayerWithUpdateTracking::Create(&m_fakeDelegate))
-        , m_surfaceLayer2(ContentLayerWithUpdateTracking::Create(&m_fakeDelegate))
-        , m_replicaLayer2(ContentLayerWithUpdateTracking::Create(&m_fakeDelegate))
+            : m_rootLayer(FakeContentLayer::Create(&m_client))
+            , m_surfaceLayer1(FakeContentLayer::Create(&m_client))
+            , m_replicaLayer1(FakeContentLayer::Create(&m_client))
+            , m_surfaceLayer2(FakeContentLayer::Create(&m_client))
+            , m_replicaLayer2(FakeContentLayer::Create(&m_client))
     {
     }
 
@@ -1306,12 +1308,15 @@ public:
         layer_tree_host()->SetViewportSize(gfx::Size(100, 100), gfx::Size(100, 100));
 
         m_rootLayer->SetBounds(gfx::Size(100, 100));
+        m_rootLayer->SetIsDrawable(true);
         m_surfaceLayer1->SetBounds(gfx::Size(100, 100));
         m_surfaceLayer1->SetForceRenderSurface(true);
         m_surfaceLayer1->SetOpacity(0.5);
+        m_surfaceLayer1->SetIsDrawable(true);
         m_surfaceLayer2->SetBounds(gfx::Size(100, 100));
         m_surfaceLayer2->SetForceRenderSurface(true);
         m_surfaceLayer2->SetOpacity(0.5);
+        m_surfaceLayer2->SetIsDrawable(true);
 
         m_surfaceLayer1->SetReplicaLayer(m_replicaLayer1.get());
         m_surfaceLayer2->SetReplicaLayer(m_replicaLayer2.get());
@@ -1329,7 +1334,8 @@ public:
         RenderPass::Id surface1RenderPassId = hostImpl->active_tree()->root_layer()->children()[0]->render_surface()->RenderPassId();
         RenderPass::Id surface2RenderPassId = hostImpl->active_tree()->root_layer()->children()[0]->children()[0]->render_surface()->RenderPassId();
 
-        switch (hostImpl->active_tree()->source_frame_number()) {
+        int source_frame = hostImpl->active_tree()->source_frame_number();
+        switch (source_frame) {
         case 0:
             EXPECT_TRUE(renderer->HaveCachedResourcesForRenderPassId(surface1RenderPassId));
             EXPECT_TRUE(renderer->HaveCachedResourcesForRenderPassId(surface2RenderPassId));
@@ -1347,27 +1353,25 @@ public:
         }
     }
 
+    virtual void DidCommitAndDrawFrame() OVERRIDE {
+        if (!TestEnded())
+            m_rootLayer->SetNeedsDisplay();
+    }
+
     virtual void AfterTest() OVERRIDE
     {
-        EXPECT_EQ(2, m_rootLayer->paintContentsCount());
-        EXPECT_EQ(2, m_surfaceLayer1->paintContentsCount());
-        EXPECT_EQ(2, m_surfaceLayer2->paintContentsCount());
-
-        // Clear layer references so LayerTreeHost dies.
-        m_rootLayer = NULL;
-        m_surfaceLayer1 = NULL;
-        m_replicaLayer1 = NULL;
-        m_surfaceLayer2 = NULL;
-        m_replicaLayer2 = NULL;
+        EXPECT_EQ(3, m_rootLayer->update_count());
+        EXPECT_EQ(3, m_surfaceLayer1->update_count());
+        EXPECT_EQ(3, m_surfaceLayer2->update_count());
     }
 
 private:
-    FakeContentLayerClient m_fakeDelegate;
-    scoped_refptr<ContentLayerWithUpdateTracking> m_rootLayer;
-    scoped_refptr<ContentLayerWithUpdateTracking> m_surfaceLayer1;
-    scoped_refptr<ContentLayerWithUpdateTracking> m_replicaLayer1;
-    scoped_refptr<ContentLayerWithUpdateTracking> m_surfaceLayer2;
-    scoped_refptr<ContentLayerWithUpdateTracking> m_replicaLayer2;
+    FakeContentLayerClient m_client;
+    scoped_refptr<FakeContentLayer> m_rootLayer;
+    scoped_refptr<FakeContentLayer> m_surfaceLayer1;
+    scoped_refptr<FakeContentLayer> m_replicaLayer1;
+    scoped_refptr<FakeContentLayer> m_surfaceLayer2;
+    scoped_refptr<FakeContentLayer> m_replicaLayer2;
 };
 
 SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostTestSurfaceNotAllocatedForLayersOutsideMemoryLimit)
@@ -1515,7 +1519,7 @@ public:
     // the beginFrame/commit pair.
     // Commits 5+6 test the path where an eviction happens during the eviction
     // recovery path.
-    virtual void DidCommitAndDrawFrame() OVERRIDE
+    virtual void DidCommit() OVERRIDE
     {
         switch (m_numCommits) {
         case 1:
@@ -1610,7 +1614,7 @@ public:
     {
         if (m_numDrawLayers == 2)
             return;
-        PostSetNeedsCommitToMainThread();
+        layer_tree_host()->root_layer()->SetNeedsDisplay();
     }
 
     virtual void CommitCompleteOnThread(LayerTreeHostImpl*) OVERRIDE