gpu: Add sync token dependencies to flush metadata.

ppapi/proxy/ppapi_command_buffer_proxy.cc

 // Copyright (c) 2012 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 "ppapi/proxy/ppapi_command_buffer_proxy.h"
 
 #include <utility>
 
 #include "base/numerics/safe_conversions.h"
 #include "ppapi/proxy/ppapi_messages.h"
@@ skipping 196 matching lines @@
 bool PpapiCommandBufferProxy::IsFenceSyncReleased(uint64_t release) {
   NOTIMPLEMENTED();
   return false;
 }
 
 void PpapiCommandBufferProxy::SignalSyncToken(const gpu::SyncToken& sync_token,
                                               const base::Closure& callback) {
   NOTIMPLEMENTED();
 }
 
+void PpapiCommandBufferProxy::WaitSyncToken(const gpu::SyncToken& sync_token) {}

[dcheng, 2017/03/14 06:53:03]

Is this a NOTIMPLEMENTED() kind of thing as well?

[sunnyps, 2017/03/15 00:03:08]

No, pepper can wait on sync tokens and GLES2Implementation will call this method
in that case. We could annotate pepper's flushes with sync tokens like we do for
command buffer proxy but it's optional.

[piman, 2017/03/15 00:30:14]

We could add a TODO to forward this to the renderer, but it's so seldom used
that I think it's ok to punt for now.

[sunnyps, 2017/03/15 00:56:12]

Done.

+
 bool PpapiCommandBufferProxy::CanWaitUnverifiedSyncToken(
-    const gpu::SyncToken* sync_token) {
+    const gpu::SyncToken& sync_token) {
   return false;
 }
 
 int32_t PpapiCommandBufferProxy::GetExtraCommandBufferData() const {
   return 0;
 }
 
 void PpapiCommandBufferProxy::SignalQuery(uint32_t query,
                                           const base::Closure& callback) {
   NOTREACHED();
@@ skipping 75 matching lines @@
   message->set_unblock(true);
   Send(message);
 
   flush_info_->flush_pending = false;
   flush_info_->resource.SetHostResource(0, 0);
   flushed_fence_sync_release_ = pending_fence_sync_release_;
 }
 
 }  // namespace proxy
 }  // namespace ppapi