[PowerProfiler] Power Profiler service should detect the sampling rate from the data provider.

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/public/browser/browser_thread.h"
 
-namespace {
-
-// Default sampling period, as recommended by Intel Power Gadget.
-// Section 3.1 of http://software.intel.com/en-us/blogs/2013/10/03/using-the-intel-power-gadget-api-on-windows
-const int kDefaultSamplePeriodMs = 50;
-
-}  // namespace
-
 namespace content {
 
 PowerProfilerService::PowerProfilerService()
     : status_(UNINITIALIZED),
-      sample_period_(base::TimeDelta::FromMilliseconds(kDefaultSamplePeriodMs)),
       data_provider_(PowerDataProvider::Create()) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // No provider supported for current platform.
   if (!data_provider_.get())
     return;
-
+  sample_period_ = data_provider_->GetSamplingRate();
   status_ = INITIALIZED;
   task_runner_ = BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
       BrowserThread::GetBlockingPool()->GetSequenceToken());
 }
 
 PowerProfilerService::PowerProfilerService(
     scoped_ptr<PowerDataProvider> provider,
     scoped_refptr<base::TaskRunner> task_runner,
     const base::TimeDelta& sample_period)
     : task_runner_(task_runner),
@@ skipping 67 matching lines @@
 
   // Get data and notify.
   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