Update from https://crrev.com/307330

cc/scheduler/scheduler_state_machine.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/scheduler/scheduler_state_machine.h"
 
 #include "base/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
 #include "base/format_macros.h"
 #include "base/logging.h"
@@ skipping 802 matching lines @@
       << AsValue()->ToString();
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
 }
 
 void SchedulerStateMachine::OnBeginImplFrameIdle() {
   DCHECK_EQ(begin_impl_frame_state_, BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
       << AsValue()->ToString();
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_IDLE;
 }
 
-bool SchedulerStateMachine::ShouldTriggerBeginImplFrameDeadlineEarly() const {
+SchedulerStateMachine::BeginImplFrameDeadlineMode
+SchedulerStateMachine::CurrentBeginImplFrameDeadlineMode() const {
+  if (ShouldTriggerBeginImplFrameDeadlineImmediately()) {
+    return BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE;
+  } else if (needs_redraw_ && pending_swaps_ < max_pending_swaps_) {
+    // We have an animation or fast input path on the impl thread that wants
+    // to draw, so don't wait too long for a new active tree.
+    // If we are swap throttled we should wait until we are unblocked.
+    return BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR;
+  } else {
+    // The impl thread doesn't have anything it wants to draw and we are just
+    // waiting for a new active tree or we are swap throttled. In short we are
+    // blocked.
+    return BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE;
+  }
+}
+
+bool SchedulerStateMachine::ShouldTriggerBeginImplFrameDeadlineImmediately()
+    const {
   // TODO(brianderson): This should take into account multiple commit sources.
 
   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
     return false;
 
   // If we've lost the output surface, end the current BeginImplFrame ASAP
   // so we can start creating the next output surface.
   if (output_surface_state_ == OUTPUT_SURFACE_LOST)
     return true;
 
@@ skipping 244 matching lines @@
       static_cast<int>(begin_impl_frame_state_),
       static_cast<int>(commit_state_),
       has_pending_tree_ ? 'T' : 'F',
       pending_tree_is_ready_for_activation_ ? 'T' : 'F',
       active_tree_needs_first_draw_ ? 'T' : 'F',
       max_pending_swaps_,
       pending_swaps_);
 }
 
 }  // namespace cc