cc: Poll for state that triggers draws (synchronous compositor only)

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 3db7e6786012b723608e7188a8c8a55ba4e6f291..fc1d582067d5cb93a96ddf622d578b51ad3844de 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -2404,6 +2404,51 @@ class LayerTreeHostTestBeginFrameNotificationShutdownWhileEnabled
 MULTI_THREAD_TEST_F(
     LayerTreeHostTestBeginFrameNotificationShutdownWhileEnabled);
 
+class LayerTreeHostTestAbortedCommitDoesntStallNextCommitWhenIdle
+    : public LayerTreeHostTest {
+ protected:
+  LayerTreeHostTestAbortedCommitDoesntStallNextCommitWhenIdle()
+      : commit_count_(0), commit_complete_count_(0) {}
+
+  virtual void InitializeSettings(LayerTreeSettings* settings) OVERRIDE {
+    settings->begin_frame_scheduling_enabled = true;
+    settings->using_synchronous_renderer_compositor = true;
+  }
+
+  virtual void BeginTest() OVERRIDE { PostSetNeedsCommitToMainThread(); }
+
+  virtual void DidCommit() OVERRIDE {
+    commit_count_++;
+    if (commit_count_ == 2) {
+      // A commit was just aborted, request a real commit now to make sure a
+      // real commit following an aborted commit will still complete and
+      // end the test even when the Impl thread is idle.
+      layer_tree_host()->SetNeedsCommit();
+    }
+  }
+
+  virtual void CommitCompleteOnThread(LayerTreeHostImpl* host_impl) OVERRIDE {
+    commit_complete_count_++;
+    if (commit_complete_count_ == 1) {
+      // Initiate an aborted commit after the first commit.
+      host_impl->SetNeedsCommit();
+    } else {
+      EndTest();
+    }
+  }
+
+  virtual void AfterTest() OVERRIDE {
+    EXPECT_EQ(commit_count_, 3);
+    EXPECT_EQ(commit_complete_count_, 2);
+  }
+
+  int commit_count_;
+  int commit_complete_count_;
+};
+
+MULTI_THREAD_TEST_F(
+    LayerTreeHostTestAbortedCommitDoesntStallNextCommitWhenIdle);
+
 class LayerTreeHostTestUninvertibleTransformDoesNotBlockActivation
     : public LayerTreeHostTest {
  protected: