Chrome power profiler service

content/browser/power_profiler/power_profiler_service.cc

+// Copyright 2014 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/power_profiler/power_profiler_service.h"
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "content/browser/power_profiler/power_data_provider_factory.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+
+PowerProfilerService::PowerProfilerService()
+    : status_(UNINITIALIZED),
+      delay_(base::TimeDelta::FromMilliseconds(50)),

[jeremy, 2014/02/16 14:09:19]

Where does this value come from?

Recommend initializing from a file constant with a comment on where this number
came from.

[Pan, 2014/02/17 03:17:15]

This value is recommended by Intel Power Gadget, considering both poll overhead
and resolution request per app.

+      data_provider_(PowerDataProviderFactory::Create()) {
+  if (data_provider_.get()) {
+      status_ = INITIALIZED;
+      task_runner_ = BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
+          BrowserThread::GetBlockingPool()->GetSequenceToken());
+  }
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

[jeremy, 2014/02/16 14:09:19]

IMHO this should be at the start of the function.

[Pan, 2014/02/17 03:17:15]

Done.

+}
+
+PowerProfilerService::PowerProfilerService(
+    scoped_ptr<PowerDataProvider> provider,
+    scoped_refptr<base::TaskRunner> task_runner,
+    const base::TimeDelta& delay)
+    : task_runner_(task_runner),
+      status_(UNINITIALIZED),
+      delay_(delay),
+      data_provider_(provider.Pass()) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (data_provider_.get())
+      status_ = INITIALIZED;
+}
+
+bool PowerProfilerService::IsAvailable() {
+  return status_ !=  UNINITIALIZED;
+}
+
+PowerProfilerService* PowerProfilerService::GetInstance() {
+  return Singleton<PowerProfilerService>::get();
+}
+
+void PowerProfilerService::AddObserver(PowerProfilerObserver* obs) {

[jeremy, 2014/02/16 14:09:19]

obs -> observer

[Pan, 2014/02/17 03:17:15]

Done.

+  if (UNINITIALIZED == status_)

[jeremy, 2014/02/16 14:09:19]

status_ == UNINITALIZED

constant on rhs in comparisons below as well.

[Pan, 2014/02/17 03:17:15]

Done.

+    return;
+
+  observers_.AddObserver(obs);
+  if (PROFILING != status_)
+    Start();
+}
+
+void PowerProfilerService::RemoveObserver(PowerProfilerObserver* obs) {
+  observers_.RemoveObserver(obs);
+
+  if (!observers_.might_have_observers())
+    Stop();
+}
+
+void PowerProfilerService::Start() {
+  DCHECK(INITIALIZED == status_);
+  status_ = PROFILING;
+
+  // send out power events immediately.

[jeremy, 2014/02/16 14:09:19]

Send

[Pan, 2014/02/17 03:17:15]

Done.

+  QueryData();
+
+  query_power_timer_.Start(FROM_HERE,
+      delay_, this, &PowerProfilerService::QueryData);
+}
+
+void PowerProfilerService::Stop() {
+  DCHECK(PROFILING == status_);
+
+  // stop timer, set status to INITIALIZED

[jeremy, 2014/02/16 14:09:19]

I think this comment is redundant.

[Pan, 2014/02/17 03:17:15]

Done.

+  query_power_timer_.Stop();
+  status_ = INITIALIZED;
+}
+
+void PowerProfilerService::QueryData() {
+  task_runner_->PostTask(
+      FROM_HERE, base::Bind(&PowerProfilerService::QueryDataOnTaskRunner,
+                            base::Unretained(this)));
+}
+
+void PowerProfilerService::Notify(const PowerEventVector& events) {
+  FOR_EACH_OBSERVER(PowerProfilerObserver, observers_, OnPowerEvent(events));
+}
+
+void PowerProfilerService::QueryDataOnTaskRunner() {
+  DCHECK(task_runner_->RunsTasksOnCurrentThread());
+  if (PROFILING != status_)
+    return;
+
+  // Get Data and Notify

[jeremy, 2014/02/16 14:09:19]

. at end of comment.

Data and Notify shouldn't be capitalized.

[Pan, 2014/02/17 03:17:15]

Done.

+  PowerEventVector events = data_provider_->GetData();
+  if (events.size() != 0) {
+    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE, base::Bind(
+        &PowerProfilerService::Notify, base::Unretained(this), events));
+  }
+}
+
+}  // namespace content