time metric: record elapsed time from when the backgrounded and purged renderer is foregrounded unti

content/renderer/render_thread_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/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <utility>
@@ skipping 878 matching lines @@
   ChildThreadImpl::current()->SetThreadPriority(
       categorized_worker_pool_->background_worker_thread_id(),
       base::ThreadPriority::BACKGROUND);
 #endif
 
   record_purge_suspend_metric_closure_.Reset(base::Bind(
       &RenderThreadImpl::RecordPurgeAndSuspendMetrics, base::Unretained(this)));
   record_purge_suspend_growth_metric_closure_.Reset(
       base::Bind(&RenderThreadImpl::RecordPurgeAndSuspendMemoryGrowthMetrics,
                  base::Unretained(this)));
+  record_first_active_paint_ = true;
+  foregrounded_time_ = base::TimeTicks::Now();
 
   base::MemoryCoordinatorClientRegistry::GetInstance()->Register(this);
 
   // If this renderer doesn't run inside the browser process, enable
   // SequencedWorkerPool. Otherwise, it should already have been enabled.
   // TODO(fdoray): Remove this once the SequencedWorkerPool to TaskScheduler
   // redirection experiment concludes https://crbug.com/622400.
   if (!command_line.HasSwitch(switches::kSingleProcess))
     base::SequencedWorkerPool::EnableForProcess();
 }
@@ skipping 737 matching lines @@
           base::MemoryState::NORMAL);
 
     record_purge_suspend_metric_closure_.Cancel();
     record_purge_suspend_metric_closure_.Reset(
         base::Bind(&RenderThreadImpl::RecordPurgeAndSuspendMetrics,
                    base::Unretained(this)));
     record_purge_suspend_growth_metric_closure_.Cancel();
     record_purge_suspend_growth_metric_closure_.Reset(
         base::Bind(&RenderThreadImpl::RecordPurgeAndSuspendMemoryGrowthMetrics,
                    base::Unretained(this)));
+    foregrounded_time_ = base::TimeTicks::Now();
   }
 }
 
 void RenderThreadImpl::OnProcessPurgeAndSuspend() {
   ChildThreadImpl::OnProcessPurgeAndSuspend();
   if (!RendererIsHidden())
     return;
 
   // TODO(bashi): Enable the tab suspension when MemoryCoordinator is enabled.
   if (base::FeatureList::IsEnabled(features::kMemoryCoordinator))
     return;
 
   if (base::FeatureList::IsEnabled(features::kPurgeAndSuspend)) {
     // TODO(tasak): After enabling MemoryCoordinator, remove this Notify
     // and follow MemoryCoordinator's request.
     base::MemoryCoordinatorClientRegistry::GetInstance()->Notify(
         base::MemoryState::SUSPENDED);
   }
   // Since purging is not a synchronous task (e.g. v8 GC, oilpan GC, ...),
   // we need to wait until the task is finished. So wait 15 seconds and
   // update purge+suspend UMA histogram.
   // TODO(tasak): use MemoryCoordinator's callback to report purge+suspend
   // UMA when MemoryCoordinator is available.
   GetRendererScheduler()->DefaultTaskRunner()->PostDelayedTask(
       FROM_HERE, record_purge_suspend_metric_closure_.callback(),
       base::TimeDelta::FromSeconds(15));
+  record_first_active_paint_ = false;
 }
 
 // TODO(tasak): Replace the following GetMallocUsage() with memory-infra
 // when it is possible to run memory-infra without tracing.
 #if defined(OS_WIN)
 namespace {
 
 static size_t GetMallocUsage() {
   // Iterate through whichever heap the CRT is using.
   HANDLE crt_heap = reinterpret_cast<HANDLE>(_get_heap_handle());
@@ skipping 743 matching lines @@
         v8::MemoryPressureLevel::kCritical);
   }
 }
 
 void RenderThreadImpl::OnRendererInterfaceRequest(
     mojom::RendererAssociatedRequest request) {
   DCHECK(!renderer_binding_.is_bound());
   renderer_binding_.Bind(std::move(request));
 }
 
+void RenderThreadImpl::OnPostWidgetUpdateVisualState() {
+  if (record_first_active_paint_)

[esprehn, 2017/01/25 03:22:17]

Can we put all of this code into RenderWidget instead and have it query the
times from the RenderThread?

[tasak, 2017/01/26 09:39:40]

I moved the code into RenderWidget.

+    return;
+
+  record_first_active_paint_ = true;
+  base::TimeDelta sample = base::TimeTicks::Now() - foregrounded_time_;
+  UMA_HISTOGRAM_TIMES("PurgeAndSuspend.Experimental.TimeToFirstActivePaint",
+                      sample);
+}
+
 }  // namespace content