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

content/browser/power_profiler/power_profiler_service_unittest.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 "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "content/browser/browser_thread_impl.h"
 #include "content/browser/power_profiler/power_profiler_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace content {
 
 namespace {
 
 const int kNumEvents = 3;
+const int kDefaultSamplePeriodMs = 50;
 
 // Provide a set number of power events.
 class TestPowerDataProvider : public PowerDataProvider {
  public:
   TestPowerDataProvider(int count) : num_events_to_send_(count) {}
   virtual ~TestPowerDataProvider() {}
 
   virtual PowerEventVector GetData() OVERRIDE {
     PowerEventVector events;
     if (num_events_to_send_ == 0)
       return events;
 
     PowerEvent event;
     event.type = PowerEvent::SOC_PACKAGE;
     event.time = base::TimeTicks::Now();
     event.value = 1.0;
     events.push_back(event);
 
     num_events_to_send_--;
     return events;
   }
 
+  virtual base::TimeDelta GetSamplingRate() OVERRIDE {
+    return base::TimeDelta::FromMilliseconds(kDefaultSamplePeriodMs);
+  }
+
  private:
   int num_events_to_send_;
   DISALLOW_COPY_AND_ASSIGN(TestPowerDataProvider);
 };
 
 class TestPowerProfilerObserver : public PowerProfilerObserver {
  public:
   TestPowerProfilerObserver()
       : valid_event_count_(0),
         total_num_events_received_(0) {}
@@ skipping 81 matching lines @@
 
   ServiceStartTest();
   AddObserverTest();
 
   run_loop.Run();
 
   RemoveObserverTest();
 }
 
 }  // namespace content