Fix failing (flaky) LayerTreeHostTestLCDNotification test.

This test failed with impl-side painting because PictureLayer did not
skip commits caused by invalidating the layer during Update.

Meanwhile, this CL has some changes that changed the flaky failures
into always-failures. The change is to make the
ThreadProxy::CommitPendingForTesting check not only if a main frame is
in progress, but also if one will happen in the future. The failure was
flaky because the commit would be requested but not happen immediately
when impl-side painting was on due to activation (if the machine was
suitably loaded at the time). I renamed CommitPendingForTesting to
MainFrameWillHappenForTesting because "CommitPending" is a specific
notion in the public API of the scheduler and I didn't want to confuse
these two.

R=ajuma, brianderson, enne
BUG=402449, 397120

Review URL: https://codereview.chromium.org/462803002

Cr-Commit-Position: refs/heads/master@{#289165}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289165 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 21 insertions, 5 deletions

diff --git a/cc/scheduler/scheduler.h b/cc/scheduler/scheduler.h
index 311a71d..ce3fed7 100644
--- a/cc/scheduler/scheduler.h
+++ b/cc/scheduler/scheduler.h
@@ -98,6 +98,13 @@ class CC_EXPORT Scheduler {
   void DidLoseOutputSurface();
   void DidCreateAndInitializeOutputSurface();
 
+  // Tests do not want to shut down until all possible BeginMainFrames have
+  // occured to prevent flakiness.
+  bool MainFrameForTestingWillHappen() const {
+    return state_machine_.CommitPending() ||
+           state_machine_.CouldSendBeginMainFrame();
+  }
+
   bool CommitPending() const { return state_machine_.CommitPending(); }
   bool RedrawPending() const { return state_machine_.RedrawPending(); }
   bool ManageTilesPending() const {
diff --git a/cc/scheduler/scheduler_state_machine.cc b/cc/scheduler/scheduler_state_machine.cc
index 723c40c..c66b650 100644
--- a/cc/scheduler/scheduler_state_machine.cc
+++ b/cc/scheduler/scheduler_state_machine.cc
@@ -418,10 +418,21 @@ bool SchedulerStateMachine::ShouldAnimate() const {
   return needs_redraw_ || needs_animate_;
 }
 
-bool SchedulerStateMachine::ShouldSendBeginMainFrame() const {
+bool SchedulerStateMachine::CouldSendBeginMainFrame() const {
   if (!needs_commit_)
     return false;
 
+  // We can not perform commits if we are not visible.
+  if (!visible_)
+    return false;
+
+  return true;
+}
+
+bool SchedulerStateMachine::ShouldSendBeginMainFrame() const {
+  if (!CouldSendBeginMainFrame())
+    return false;
+
   // Only send BeginMainFrame when there isn't another commit pending already.
   if (commit_state_ != COMMIT_STATE_IDLE)
     return false;
@@ -433,10 +444,6 @@ bool SchedulerStateMachine::ShouldSendBeginMainFrame() const {
     return false;
   }
 
-  // We do not need commits if we are not visible.
-  if (!visible_)
-    return false;
-
   // We want to start the first commit after we get a new output surface ASAP.
   if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT)
     return true;
diff --git a/cc/scheduler/scheduler_state_machine.h b/cc/scheduler/scheduler_state_machine.h
index d92a352f..bb033a1 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -235,6 +235,8 @@ class CC_EXPORT SchedulerStateMachine {
     continuous_painting_ = continuous_painting;
   }
 
+  bool CouldSendBeginMainFrame() const;
+
  protected:
   bool BeginFrameNeededToAnimateOrDraw() const;
   bool ProactiveBeginFrameWanted() const;