Trace background/visibility events

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 493 matching lines @@
   is_loading_ = is_loading;
   if (!view_)
     return;
   view_->SetIsLoading(is_loading);
 }
 
 void RenderWidgetHostImpl::WasHidden() {
   if (is_hidden_)
     return;
 
+  TRACE_EVENT0("browser", "RenderWidgetHostImpl::WasHidden");

[no sievers, 2015/03/25 21:56:10]

maybe this should be in the 'renderer_host' category?

[jdduke (slow), 2015/03/25 22:19:23]

Absolutely, I even had that in my local branch =/.

   is_hidden_ = true;
 
   // Don't bother reporting hung state when we aren't active.
   StopHangMonitorTimeout();
 
   // If we have a renderer, then inform it that we are being hidden so it can
   // reduce its resource utilization.
   Send(new ViewMsg_WasHidden(routing_id_));
 
   // Tell the RenderProcessHost we were hidden.
   process_->WidgetHidden();
 
   bool is_visible = false;
   NotificationService::current()->Notify(
       NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
       Source<RenderWidgetHost>(this),
       Details<bool>(&is_visible));
 }
 
 void RenderWidgetHostImpl::WasShown(const ui::LatencyInfo& latency_info) {
   if (!is_hidden_)
     return;
+
+  TRACE_EVENT0("browser", "RenderWidgetHostImpl::WasShown");
   is_hidden_ = false;
 
   SendScreenRects();
 
   // When hidden, timeout monitoring for input events is disabled. Restore it
   // now to ensure consistent hang detection.
   if (in_flight_event_count_)
     RestartHangMonitorTimeout();
 
   // Always repaint on restore.
@@ skipping 1573 matching lines @@
 }
 #endif
 
 SkColorType RenderWidgetHostImpl::PreferredReadbackFormat() {
   if (view_)
     return view_->PreferredReadbackFormat();
   return kN32_SkColorType;
 }
 
 }  // namespace content