Remove LatencyInfo::sequence_number. (May break metrics).

content/browser/renderer_host/render_widget_host_impl.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 "content/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 
 #include <set>
 #include <tuple>
@@ skipping 1485 matching lines @@
 }
 
 void RenderWidgetHostImpl::GetSnapshotFromBrowser(
     const GetSnapshotFromBrowserCallback& callback,
     bool from_surface) {
   int id = next_browser_snapshot_id_++;
   if (from_surface) {
     pending_surface_browser_snapshots_.insert(std::make_pair(id, callback));
     ui::LatencyInfo latency_info;
     latency_info.AddLatencyNumber(ui::BROWSER_SNAPSHOT_FRAME_NUMBER_COMPONENT,
-                                  0, id);
+                                  id);
     Send(new ViewMsg_ForceRedraw(GetRoutingID(), latency_info));
     return;
   }
 
 #if defined(OS_MACOSX)
   // MacOS version of underlying GrabViewSnapshot() blocks while
   // display/GPU are in a power-saving mode, so make sure display
   // does not go to sleep for the duration of reading a snapshot.
   if (pending_browser_snapshots_.empty())
     GetWakeLock()->RequestWakeLock();
 #endif
   pending_browser_snapshots_.insert(std::make_pair(id, callback));
   ui::LatencyInfo latency_info;
-  latency_info.AddLatencyNumber(ui::BROWSER_SNAPSHOT_FRAME_NUMBER_COMPONENT, 0,
+  latency_info.AddLatencyNumber(ui::BROWSER_SNAPSHOT_FRAME_NUMBER_COMPONENT,
                                 id);
   Send(new ViewMsg_ForceRedraw(GetRoutingID(), latency_info));
 }
 
 const NativeWebKeyboardEvent*
     RenderWidgetHostImpl::GetLastKeyboardEvent() const {
   return input_router_->GetLastKeyboardEvent();
 }
 
 void RenderWidgetHostImpl::SelectionChanged(const base::string16& text,
@@ skipping 294 matching lines @@
   NotifyNewContentRenderingTimeoutForTesting();
   if (view_)
     view_->ClearCompositorFrame();
 }
 
 void RenderWidgetHostImpl::OnGpuSwapBuffersCompletedInternal(
     const ui::LatencyInfo& latency_info) {
   ui::LatencyInfo::LatencyComponent window_snapshot_component;
   if (latency_info.FindLatency(ui::BROWSER_SNAPSHOT_FRAME_NUMBER_COMPONENT,
                                GetLatencyComponentId(),
                                &window_snapshot_component)) {

[ccameron, 2017/06/29 20:52:18]

Looks reasonable (first not-just-delete change).

-    int sequence_number =
-        static_cast<int>(window_snapshot_component.sequence_number);
+    static int snapshot_id = 0;
+    ++snapshot_id;
 #if defined(OS_MACOSX) || defined(OS_WIN)
     // On Mac, when using CoreAnimation, or Win32 when using GDI, there is a
     // delay between when content is drawn to the screen, and when the
     // snapshot will actually pick up that content. Insert a manual delay of
     // 1/6th of a second (to simulate 10 frames at 60 fps) before actually
     // taking the snapshot.
     base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
         FROM_HERE,
         base::Bind(&RenderWidgetHostImpl::WindowSnapshotReachedScreen,
-                   weak_factory_.GetWeakPtr(), sequence_number),
+                   weak_factory_.GetWeakPtr(), snapshot_id),
         base::TimeDelta::FromSecondsD(1. / 6));
 #else
-    WindowSnapshotReachedScreen(sequence_number);
+    WindowSnapshotReachedScreen(snapshot_id);
 #endif
   }
 
   latency_tracker_.OnGpuSwapBuffersCompleted(latency_info);
 }
 
 void RenderWidgetHostImpl::OnRenderProcessGone(int status, int exit_code) {
   // RenderFrameHost owns a RenderWidgetHost when it needs one, in which case
   // it handles destruction.
   if (!owned_by_render_frame_host_) {
@@ skipping 835 matching lines @@
           device::mojom::WakeLockType::PreventDisplaySleep,
           device::mojom::WakeLockReason::ReasonOther, "GetSnapshot",
           std::move(request));
     }
   }
   return wake_lock_.get();
 }
 #endif
 
 }  // namespace content