[Tentaive patch for discussion] Add Purge+Suspend metrics as UMA.

content/browser/renderer_host/render_process_host_impl.cc

 // Copyright 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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 977 matching lines @@
 
   if (!gpu_observer_registered_) {
     gpu_observer_registered_ = true;
     ui::GpuSwitchingManager::GetInstance()->AddObserver(this);
   }
 
   power_monitor_broadcaster_.Init();
 
   is_initialized_ = true;
   init_time_ = base::TimeTicks::Now();
+  last_purge_and_suspend_time_ = base::TimeTicks::TimeTicks();
   return true;
 }
 
 std::unique_ptr<IPC::ChannelProxy> RenderProcessHostImpl::CreateChannelProxy(
     const std::string& channel_id) {
   scoped_refptr<base::SingleThreadTaskRunner> runner =
       BrowserThread::GetTaskRunnerForThread(BrowserThread::IO);
   IPC::mojom::ChannelBootstrapPtr bootstrap;
   GetRemoteInterfaces()->GetInterface(&bootstrap);
   std::unique_ptr<IPC::ChannelFactory> channel_factory =
@@ skipping 424 matching lines @@
   Cleanup();
 }
 
 bool RenderProcessHostImpl::IsWorkerRefCountDisabled() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   return is_worker_ref_count_disabled_;
 }
 
 void RenderProcessHostImpl::PurgeAndSuspend() {
   Send(new ChildProcessMsg_PurgeAndSuspend());
+  last_purge_and_suspend_time_ = base::TimeTicks::Now();
+}
+
+const base::TimeTicks& RenderProcessHostImpl::GetLastPurgeAndSuspendTime()
+    const {
+  return last_purge_and_suspend_time_;
 }
 
 mojom::RouteProvider* RenderProcessHostImpl::GetRemoteRouteProvider() {
   if (!remote_route_provider_) {
     DCHECK(channel_);
     channel_->GetRemoteAssociatedInterface(&remote_route_provider_);
   }
   return remote_route_provider_.get();
 }
 
@@ skipping 1593 matching lines @@
   LOG(ERROR) << "Terminating render process for bad Mojo message: " << error;
 
   // The ReceivedBadMessage call below will trigger a DumpWithoutCrashing. Alias
   // enough information here so that we can determine what the bad message was.
   base::debug::Alias(&error);
   bad_message::ReceivedBadMessage(process.get(),
                                   bad_message::RPH_MOJO_PROCESS_ERROR);
 }
 
 }  // namespace content