cc: Send shared variables between main and impl side using the channel

cc/trees/layer_tree_host_unittest_proxy.cc

Index: cc/trees/layer_tree_host_unittest_proxy.cc
diff --git a/cc/trees/layer_tree_host_unittest_proxy.cc b/cc/trees/layer_tree_host_unittest_proxy.cc
index d4057cfa10a2a17ba9f8f246f4be0e4a3bda724a..481353535c157e25ba1f3da42dc2a77ff30efe4e 100644
--- a/cc/trees/layer_tree_host_unittest_proxy.cc
+++ b/cc/trees/layer_tree_host_unittest_proxy.cc
@@ -287,4 +287,68 @@ class ThreadProxyTestSetNeedsCommitWhileAnimating : public ThreadProxyTest {
 
 THREAD_PROXY_TEST_F(ThreadProxyTestSetNeedsCommitWhileAnimating);
 
+class ThreadProxyTestCommitWaitsForActivation : public ThreadProxyTest {
+ protected:
+  ThreadProxyTestCommitWaitsForActivation() : commits_completed_(0) {}
+  ~ThreadProxyTestCommitWaitsForActivation() override {}
+
+  void BeginTest() override { proxy()->SetNeedsCommit(); }
+
+  void ScheduledActionCommit() override {
+    switch (commits_completed_) {
+      case 0:
+        // The first commit does not wait for activation. Verify that the
+        // completion event is cleared.
+        EXPECT_EQ(nullptr, ThreadProxyImplOnly().commit_completion_event);
+        EXPECT_EQ(false,
+                  ThreadProxyImplOnly().next_commit_waits_for_activation);
+        break;
+      case 1:
+        // The second commit should be held until activation.
+        EXPECT_NE(nullptr, ThreadProxyImplOnly().commit_completion_event);
+        EXPECT_EQ(true, ThreadProxyImplOnly().next_commit_waits_for_activation);
+        break;
+      case 2:
+        // The third commit should not wait for activation.
+        EXPECT_EQ(nullptr, ThreadProxyImplOnly().commit_completion_event);
+        EXPECT_EQ(false,
+                  ThreadProxyImplOnly().next_commit_waits_for_activation);
+    }
+  }
+
+  void DidActivateSyncTree() override {
+    // The next_commit_waits_for_activation should have been cleared after the
+    // sync tree is activated.
+    EXPECT_EQ(false, ThreadProxyImplOnly().next_commit_waits_for_activation);
+  }
+
+  void DidCommit() override {
+    switch (commits_completed_) {
+      case 0:
+        // The first commit has been completed. Set next commit waits for
+        // activation and start another commit.
+        commits_completed_++;
+        proxy()->SetNextCommitWaitsForActivation();
+        proxy()->SetNeedsCommit();
+      case 1:
+        // Start another commit to verify that this is not held until
+        // activation.
+        commits_completed_++;
+        proxy()->SetNeedsCommit();
+      case 2:
+        commits_completed_++;
+        EndTest();
+    }
+  }
+
+  void AfterTest() override { EXPECT_EQ(3, commits_completed_); }
+
+ private:
+  int commits_completed_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadProxyTestCommitWaitsForActivation);
+};
+
+THREAD_PROXY_TEST_F(ThreadProxyTestCommitWaitsForActivation);
+
 }  // namespace cc