Do glFinish before sending snapshot latency info to browser

gpu/ipc/service/pass_through_image_transport_surface.cc

 // Copyright 2016 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 "gpu/ipc/service/pass_through_image_transport_surface.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "build/build_config.h"
@@ skipping 184 matching lines @@
       new std::vector<ui::LatencyInfo>());
   latency_info->swap(latency_info_);
 
   return latency_info;
 }
 
 void PassThroughImageTransportSurface::FinishSwapBuffers(
     std::unique_ptr<std::vector<ui::LatencyInfo>> latency_info,
     gfx::SwapResult result) {
   base::TimeTicks swap_ack_time = base::TimeTicks::Now();
+  bool has_browser_snapshot_request = false;
   for (auto& latency : *latency_info) {
     latency.AddLatencyNumberWithTimestamp(
         ui::INPUT_EVENT_LATENCY_TERMINATED_FRAME_SWAP_COMPONENT, 0, 0,
         swap_ack_time, 1);
+    has_browser_snapshot_request |= latency.FindLatency(
+        ui::BROWSER_SNAPSHOT_FRAME_NUMBER_COMPONENT, nullptr);
   }
+  if (has_browser_snapshot_request)
+    WaitForSnapshotRendering();
 
   if (delegate_) {
     SwapBuffersCompleteParams params;
     params.latency_info = std::move(*latency_info);
     params.result = result;
     delegate_->DidSwapBuffersComplete(std::move(params));
   }
 }
 
 void PassThroughImageTransportSurface::FinishSwapBuffersAsync(
     std::unique_ptr<std::vector<ui::LatencyInfo>> latency_info,
     GLSurface::SwapCompletionCallback callback,
     gfx::SwapResult result) {
   FinishSwapBuffers(std::move(latency_info), result);
   callback.Run(result);
 }
 
 }  // namespace gpu