cc: Adding DidFinishImplFrame to LTHI.

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 f2ed38e5fa409c2e0841a8d43d7eea03190732a4..ab406844c3bd130f8839d39c148c40cc70e05ac9 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -2308,7 +2308,8 @@ class LayerTreeHostTestDeferCommits : public LayerTreeHostTest {
 
   void BeginTest() override { PostSetNeedsCommitToMainThread(); }
 
-  void WillBeginImplFrame(const BeginFrameArgs& args) override {
+  void WillBeginImplFrameOnThread(LayerTreeHostImpl* host_impl,
+                                  const BeginFrameArgs& args) override {
     num_will_begin_impl_frame_++;
     switch (num_will_begin_impl_frame_) {
       case 1:
@@ -5512,6 +5513,61 @@ class LayerTreeHostTestContinuousPainting : public LayerTreeHostTest {
 
 MULTI_THREAD_TEST_F(LayerTreeHostTestContinuousPainting);
 
+class LayerTreeHostTestWillBeginImplFrameHasDidFinishImplFrame
+    : public LayerTreeHostTest {
+ public:
+  enum { kExpectedNumImplFrames = 10 };
+
+  LayerTreeHostTestWillBeginImplFrameHasDidFinishImplFrame()
+      : will_begin_impl_frame_count_(0), did_finish_impl_frame_count_(0) {}
+
+  void BeginTest() override {
+    // Kick off the test with a commit.
+    PostSetNeedsCommitToMainThread();
+  }
+
+  void WillBeginImplFrameOnThread(LayerTreeHostImpl* host_impl,
+                                  const BeginFrameArgs& args) override {
+    EXPECT_EQ(will_begin_impl_frame_count_, did_finish_impl_frame_count_);
+    EXPECT_FALSE(TestEnded());
+    will_begin_impl_frame_count_++;
+  }
+
+  void DidFinishImplFrameOnThread(LayerTreeHostImpl* host_impl) override {
+    did_finish_impl_frame_count_++;
+    EXPECT_EQ(will_begin_impl_frame_count_, did_finish_impl_frame_count_);
+
+    // Request a number of commits to cause multiple impl frames. We expect to
+    // get one more impl frames than the number of commits requested because
+    // after a commit it takes one frame to become idle.
+    if (did_finish_impl_frame_count_ < kExpectedNumImplFrames - 1)
+      PostSetNeedsCommitToMainThread();
+  }
+
+  void SendBeginMainFrameNotExpectedSoon() override { EndTest(); }
+
+  void AfterTest() override {
+    EXPECT_GT(will_begin_impl_frame_count_, 0);
+    EXPECT_GT(did_finish_impl_frame_count_, 0);
+    EXPECT_EQ(will_begin_impl_frame_count_, did_finish_impl_frame_count_);
+
+    // TODO(mithro): Figure out why the multithread version of this test
+    // sometimes has one more frame then expected. Possibly related to
+    // http://crbug.com/443185
+    if (!HasImplThread()) {
+      EXPECT_EQ(will_begin_impl_frame_count_, kExpectedNumImplFrames);
+      EXPECT_EQ(did_finish_impl_frame_count_, kExpectedNumImplFrames);
+    }
+  }
+
+ private:
+  int will_begin_impl_frame_count_;
+  int did_finish_impl_frame_count_;
+};
+
+SINGLE_AND_MULTI_THREAD_TEST_F(
+    LayerTreeHostTestWillBeginImplFrameHasDidFinishImplFrame);
+
 class LayerTreeHostTestSendBeginFramesToChildren : public LayerTreeHostTest {
  public:
   LayerTreeHostTestSendBeginFramesToChildren()