Add |notify_client_on_reading_change| flag to sensor configuration

device/generic_sensor/public/cpp/platform_sensor_configuration.h

 // Copyright 2016 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.
 
 #ifndef DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_CONFIGURATION_H_
 #define DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_CONFIGURATION_H_
 
 #include "base/logging.h"
 #include "device/generic_sensor/public/cpp/generic_sensor_public_export.h"
 
 namespace device {
 
 class DEVICE_GENERIC_SENSOR_PUBLIC_EXPORT PlatformSensorConfiguration {
  public:
   PlatformSensorConfiguration();
   explicit PlatformSensorConfiguration(double frequency);
   ~PlatformSensorConfiguration();
 
   bool operator==(const PlatformSensorConfiguration& other) const;
 
   // Platform dependent implementations can override this operator if different
   // optimal configuration comparison is required. By default, only frequency is
   // used to compare two configurations.
   virtual bool operator>(const PlatformSensorConfiguration& other) const;
 
   void set_frequency(double frequency);
   double frequency() const { return frequency_; }
 
+  void set_notify_client_on_reading_change(
+      bool notify_client_on_reading_change) {
+    notify_client_on_reading_change_ = notify_client_on_reading_change;
+  }
+  bool notify_client_on_reading_change() const {
+    return notify_client_on_reading_change_;
+  }
+
  private:
   double frequency_ = 1.0;  // 1 Hz by default.
+  bool notify_client_on_reading_change_ = true;

[Reilly Grant (use Gerrit), 2017/06/09 18:03:39]

Because only ON_CHANGE sensors generate notifications and the goal of this patch
is to suppress them when the client is going to be polling shared memory instead
I would name this "suppress_on_change_events" and default to false.

[juncai, 2017/06/09 19:00:51]

Done.

 };
 
 }  // namespace device
 
 #endif  // DEVICE_SENSORS_PLATFORM_SENSOR_CONFIGURATION_H_