[cc] Fix CompositorFrameSinkSupport BeginFrameAck interface.

cc/output/begin_frame_args.h

 // Copyright 2013 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.
 
 #ifndef CC_OUTPUT_BEGIN_FRAME_ARGS_H_
 #define CC_OUTPUT_BEGIN_FRAME_ARGS_H_
 
 #include <stdint.h>
 #include <memory>
 
@@ skipping 107 matching lines @@
 
 // Sent by a BeginFrameObserver as acknowledgment of completing a BeginFrame.
 struct CC_EXPORT BeginFrameAck {
   BeginFrameAck();
   BeginFrameAck(uint32_t source_id,
                 uint64_t sequence_number,
                 uint64_t latest_confirmed_sequence_number,
                 uint32_t remaining_frames,
                 bool has_damage);
 
+  // Creates a BeginFrameAck for a manual BeginFrame. Used when clients produce
+  // a CompositorFrame without prior BeginFrame, e.g. for synchronous drawing.
+  static BeginFrameAck CreateManualAckWithDamage();
+
   // Sequence number of the BeginFrame that is acknowledged.
   uint64_t sequence_number;
 
   // Sequence number of the latest BeginFrame that was positively acknowledged
   // (confirmed) by the observer.
   //
   // There are two scenarios for a positive acknowledgment:
   //  a) All of the observer's pending updates led to successful damage (e.g. a
   //     CompositorFrame or a damaged surface).
   //  b) The observer did not have any updates and thus did not need to
@@ skipping 31 matching lines @@
   uint32_t remaining_frames;
 
   // |true| if the observer has produced damage (e.g. sent a CompositorFrame or
   // damaged a surface) as part of responding to the BeginFrame.
   bool has_damage;
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_BEGIN_FRAME_ARGS_H_