cc: Add MainAndImplFrameTimeDelta UMA.

cc/scheduler/scheduler_unittest.cc

Index: cc/scheduler/scheduler_unittest.cc
diff --git a/cc/scheduler/scheduler_unittest.cc b/cc/scheduler/scheduler_unittest.cc
index 9a30c34ba89444efde1add14f2e5c0f94b589ec2..f2046cc886acf1aad8e31500f188348bafe13d12 100644
--- a/cc/scheduler/scheduler_unittest.cc
+++ b/cc/scheduler/scheduler_unittest.cc
@@ -1483,6 +1483,43 @@ TEST_F(SchedulerTest, MainFrameNotSkippedAfterLateCommit_DrawEstimateTooLong) {
       CheckMainFrameSkippedAfterLateCommit(expect_send_begin_main_frame));
 }
 
+// If the BeginMainFrame aborts, it doesn't actually insert a frame into the
+// queue, which means there is no latency to recover.
+TEST_F(SchedulerTest, MainFrameNotSkippedAfterLateAbort) {
+  scheduler_settings_.use_external_begin_frame_source = true;
+  SetUpScheduler(true);
+
+  // Use fast estimates so we think we can recover latency if needed.
+  fake_compositor_timing_history_->SetAllEstimatesTo(kFastDuration);
+
+  // Impl thread hits deadline before BeginMainFrame aborts.
+  scheduler_->SetNeedsBeginMainFrame();
+  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
+  EXPECT_SCOPED(AdvanceFrame());
+  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
+  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
+  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
+  scheduler_->NotifyBeginMainFrameStarted(base::TimeTicks());
+  EXPECT_ACTION("SetNeedsBeginFrames(true)", client_, 0, 3);
+  EXPECT_ACTION("WillBeginImplFrame", client_, 1, 3);
+  EXPECT_ACTION("ScheduledActionSendBeginMainFrame", client_, 2, 3);
+  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
+
+  // After aborting the frame, make sure we don't skip the
+  // next BeginMainFrame.
+  client_->Reset();
+  scheduler_->BeginMainFrameAborted(CommitEarlyOutReason::FINISHED_NO_UPDATES);
+  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
+  scheduler_->SetNeedsBeginMainFrame();
+  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
+  EXPECT_SCOPED(AdvanceFrame());
+  EXPECT_FALSE(scheduler_->MainThreadMissedLastDeadline());
+  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
+  EXPECT_TRUE(scheduler_->MainThreadMissedLastDeadline());
+  EXPECT_TRUE(client_->HasAction("WillBeginImplFrame"));
+  EXPECT_TRUE(client_->HasAction("ScheduledActionSendBeginMainFrame"));
+}
+
 void SchedulerTest::ImplFrameSkippedAfterLateSwapAck(
     bool swap_ack_before_deadline) {
   // To get into a high latency state, this test disables automatic swap acks.