Update from https://crrev.com/320931

cc/base/swap_promise.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_BASE_SWAP_PROMISE_H_
-#define CC_BASE_SWAP_PROMISE_H_
-
-#include "cc/output/compositor_frame_metadata.h"
-
-namespace cc {
-
-// When a change to the compositor's state/invalidation/whatever happens, a
-// Swap Promise can be inserted into LayerTreeHost/LayerTreeImpl, to track
-// whether the compositor's reply to the new state/invaliadtion/whatever is
-// completed in the compositor, i.e. the compositor knows it has been sent
-// to its output or not.
-//
-// If the new compositor state is sent to the output, SwapPromise::DidSwap()
-// will be called, and if the compositor fails to send its new state to the
-// output, SwapPromise::DidNotSwap() will be called.
-//
-// Client wishes to use SwapPromise should have a subclass that defines
-// the behavior of DidSwap() and DidNotSwap(). Notice that the promise can
-// be broken at either main or impl thread, e.g. commit fails on main thread,
-// new frame data has no actual damage so LayerTreeHostImpl::SwapBuffers()
-// bails out early on impl thread, so don't assume that DidSwap() and
-// DidNotSwap() are called at a particular thread. It is better to let the
-// subclass carry thread-safe member data and operate on that member data in
-// DidSwap() and DidNotSwap().
-class CC_EXPORT SwapPromise {
- public:
-  enum DidNotSwapReason {
-    DID_NOT_SWAP_UNKNOWN,
-    SWAP_FAILS,
-    COMMIT_FAILS,
-    COMMIT_NO_UPDATE,
-  };
-
-  SwapPromise() {}
-  virtual ~SwapPromise() {}
-
-  virtual void DidSwap(CompositorFrameMetadata* metadata) = 0;
-  virtual void DidNotSwap(DidNotSwapReason reason) = 0;
-
-  // A non-zero trace id identifies a trace flow object that is embedded in the
-  // swap promise. This can be used for registering additional flow steps to
-  // visualize the object's path through the system.
-  virtual int64 TraceId() const = 0;
-};
-
-}  // namespace cc
-
-#endif  // CC_BASE_SWAP_PROMISE_H_