cc: Don't swap throttle BeginMainFrame just after swapping

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/format_macros.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
@@ skipping 446 matching lines @@
     return true;
 
   // After this point, we only start a commit once per frame.
   if (HasSentBeginMainFrameThisFrame())
     return false;
 
   // We shouldn't normally accept commits if there isn't an OutputSurface.
   if (!HasInitializedOutputSurface())
     return false;
 
-  // SwapAck throttle the BeginMainFrames
+  // SwapAck throttle the BeginMainFrames unless we just swapped.
   // TODO(brianderson): Remove this restriction to improve throughput.
-  if (pending_swaps_ >= max_pending_swaps_)
+  bool just_swapped_in_deadline =
+      begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE &&
+      HasSwappedThisFrame();
+  if (pending_swaps_ >= max_pending_swaps_ && !just_swapped_in_deadline)
     return false;
 
   if (skip_begin_main_frame_to_reduce_latency_)
     return false;
 
   return true;
 }
 
 bool SchedulerStateMachine::ShouldCommit() const {
   if (commit_state_ != COMMIT_STATE_READY_TO_COMMIT)
@@ skipping 587 matching lines @@
     case OUTPUT_SURFACE_ACTIVE:
     case OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT:
     case OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION:
       return true;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace cc