cc: Make SingleThreadProxy ignore commit requests inside Layout().

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 7843fb45ae98c400d9ce51ac8f14e5a319aaba70..be879af1384d097e5b7d9ef53ec4ea1603c10248 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -86,6 +86,46 @@ class LayerTreeHostTest : public LayerTreeTest {
   PrioritizedResourceManager* contents_texture_manager_;
 };
 
+class LayerTreeHostTestSetNeedsCommitInsideLayout : public LayerTreeHostTest {
+ protected:
+  void BeginTest() override { PostSetNeedsCommitToMainThread(); }
+
+  void Layout() override {
+    // This shouldn't cause a second commit to happen.
+    layer_tree_host()->SetNeedsCommit();
+  }
+
+  void DidCommit() override {
+    EXPECT_EQ(1, layer_tree_host()->source_frame_number());
+    EndTest();
+  }
+
+  void AfterTest() override {}
+};
+
+SINGLE_AND_MULTI_THREAD_IMPL_TEST_F(
+    LayerTreeHostTestSetNeedsCommitInsideLayout);
+
+class LayerTreeHostTestSetNeedsUpdateInsideLayout : public LayerTreeHostTest {
+ protected:
+  void BeginTest() override { PostSetNeedsCommitToMainThread(); }
+
+  void Layout() override {
+    // This shouldn't cause a second commit to happen.
+    layer_tree_host()->SetNeedsUpdateLayers();
+  }
+
+  void DidCommit() override {
+    EXPECT_EQ(1, layer_tree_host()->source_frame_number());
+    EndTest();
+  }
+
+  void AfterTest() override {}
+};
+
+SINGLE_AND_MULTI_THREAD_IMPL_TEST_F(
+    LayerTreeHostTestSetNeedsUpdateInsideLayout);
+
 // Test if the LTHI receives ReadyToActivate notifications from the TileManager
 // when no raster tasks get scheduled.
 class LayerTreeHostTestReadyToActivateEmpty : public LayerTreeHostTest {