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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "device_sensor_event_pump.h"
      6 
      7 #include "base/logging.h"
      8 #include "content/public/renderer/render_thread.h"
      9 
     10 namespace content {
     11 
     12 // Default interval between successive polls, should take into account the
     13 // value of |kInertialSensorIntervalMillis| in
     14 // content/browser/device_sensors/inertial_sensor_consts.h.
     15 const int DeviceSensorEventPump::kDefaultPumpDelayMillis = 50;
     16 
     17 int DeviceSensorEventPump::GetDelayMillis() const {
     18   return pump_delay_millis_;
     19 }
     20 
     21 DeviceSensorEventPump::DeviceSensorEventPump()
     22     : pump_delay_millis_(kDefaultPumpDelayMillis),
     23       state_(STOPPED) {
     24 }
     25 
     26 DeviceSensorEventPump::DeviceSensorEventPump(int pump_delay_millis)
     27     : pump_delay_millis_(pump_delay_millis),
     28       state_(STOPPED) {
     29   DCHECK_GE(pump_delay_millis_, 0);
     30 }
     31 
     32 DeviceSensorEventPump::~DeviceSensorEventPump() {
     33 }
     34 
     35 bool DeviceSensorEventPump::RequestStart() {
     36   DVLOG(2) << "requested start";
     37 
     38   if (state_ != STOPPED)
     39     return false;
     40 
     41   DCHECK(!timer_.IsRunning());
     42 
     43   if (SendStartMessage()) {
     44     state_ = PENDING_START;
     45     return true;
     46   }
     47   return false;
     48 }
     49 
     50 bool DeviceSensorEventPump::Stop() {
     51   DVLOG(2) << "stop";
     52 
     53   if (state_ == STOPPED)
     54     return true;
     55 
     56   DCHECK((state_ == PENDING_START && !timer_.IsRunning()) ||
     57       (state_ == RUNNING && timer_.IsRunning()));
     58 
     59   if (timer_.IsRunning())
     60     timer_.Stop();
     61   SendStopMessage();
     62   state_ = STOPPED;
     63   return true;
     64 }
     65 
     66 void DeviceSensorEventPump::Attach(RenderThread* thread) {
     67   if (!thread)
     68     return;
     69   thread->AddObserver(this);
     70 }
     71 
     72 void DeviceSensorEventPump::OnDidStart(base::SharedMemoryHandle handle) {
     73   DVLOG(2) << "did start sensor event pump";
     74 
     75   if (state_ != PENDING_START)
     76     return;
     77 
     78   DCHECK(!timer_.IsRunning());
     79 
     80   if (InitializeReader(handle)) {
     81     timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(GetDelayMillis()),
     82                  this, &DeviceSensorEventPump::FireEvent);
     83     state_ = RUNNING;
     84   }
     85 }
     86 
     87 }  // namespace content
     88