mac: Add a metric for the time blocked by WaitForSurface().

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 <utility>
 
@@ skipping 787 matching lines @@
   // request to the renderer to paint the view if required.
   if (!repaint_ack_pending_ && !resize_ack_pending_) {
     repaint_start_time_ = TimeTicks::Now();
     repaint_ack_pending_ = true;
     TRACE_EVENT_ASYNC_BEGIN0(
         "renderer_host", "RenderWidgetHostImpl::repaint_ack_pending_", this);
     Send(new ViewMsg_Repaint(routing_id_, view_size));
   }
 
   TimeDelta max_delay = TimeDelta::FromMilliseconds(kPaintMsgTimeoutMS);
-  TimeTicks end_time = TimeTicks::Now() + max_delay;
+  TimeTicks start_time = TimeTicks::Now();
+  TimeTicks end_time = start_time + max_delay;
   do {
     TRACE_EVENT0("renderer_host", "WaitForSurface::WaitForUpdate");
 
     // When we have asked the RenderWidget to resize, and we are still waiting
     // on a response, block for a little while to see if we can't get a response
     // before returning the old (incorrectly sized) backing store.
     IPC::Message msg;
     if (RenderWidgetResizeHelper::Get()->WaitForSingleTaskToRun(max_delay)) {
 
       // For auto-resized views, current_size_ determines the view_size and it
       // may have changed during the handling of an UpdateRect message.
       if (auto_resize_enabled_)
         view_size = current_size_;
 
       // Break now if we got a backing store or accelerated surface of the
       // correct size.
       if (view_->HasAcceleratedSurface(view_size))
         return;
     } else {
       TRACE_EVENT0("renderer_host", "WaitForSurface::Timeout");
       break;
     }
 
     // Loop if we still have time left and haven't gotten a properly sized
     // BackingStore yet. This is necessary to support the GPU path which
     // typically has multiple frames pipelined -- we may need to skip one or two
     // BackingStore messages to get to the latest.
     max_delay = end_time - TimeTicks::Now();
   } while (max_delay > TimeDelta::FromSeconds(0));
+

[ccameron, 2015/01/06 02:14:21]

It should be possible to combine the base::TimeTicks::Now() from lines 837 and
840 (maybe have start_time, current_time, end_time). Not a huge difference,
though.

[erikchen, 2015/01/06 03:23:16]

It saves a call to TimeTicks::Now(), plus the original code was structured oddly
anyways. Done.

+  TimeDelta wait_duration = TimeTicks::Now() - start_time;
+  UMA_HISTOGRAM_CUSTOM_TIMES("OSX.RendererHost.SurfaceWaitTime", wait_duration,
+                             TimeDelta::FromMilliseconds(1),
+                             TimeDelta::FromMilliseconds(200), 50);
 }
 #endif
 
 bool RenderWidgetHostImpl::ScheduleComposite() {
   if (is_hidden_ || current_size_.IsEmpty() || repaint_ack_pending_ ||
       resize_ack_pending_) {
     return false;
   }
 
   // Send out a request to the renderer to paint the view if required.
@@ skipping 1316 matching lines @@
 }
 #endif
 
 SkColorType RenderWidgetHostImpl::PreferredReadbackFormat() {
   if (view_)
     return view_->PreferredReadbackFormat();
   return kN32_SkColorType;
 }
 
 }  // namespace content