[Sensors] Improvements in shared buffer managing

device/generic_sensor/platform_sensor_provider_base.h

Index: device/generic_sensor/platform_sensor_provider_base.h
diff --git a/device/generic_sensor/platform_sensor_provider_base.h b/device/generic_sensor/platform_sensor_provider_base.h
index 6d38d8596f24f64e2a9226bd6d232c73dddf5673..b9ff3232a8cb7b5d71ac01a2a09e6202b85d96d0 100644
--- a/device/generic_sensor/platform_sensor_provider_base.h
+++ b/device/generic_sensor/platform_sensor_provider_base.h
@@ -17,9 +17,7 @@ namespace device {
 class PlatformSensorProviderBase : public base::NonThreadSafe {
  public:
   // Creates new instance of PlatformSensor.
-  scoped_refptr<PlatformSensor> CreateSensor(mojom::SensorType type,
-                                             uint64_t size,
-                                             uint64_t offset);
+  scoped_refptr<PlatformSensor> CreateSensor(mojom::SensorType type);
 
   // Gets previously created instance of PlatformSensor by sensor type |type|.
   scoped_refptr<PlatformSensor> GetSensor(mojom::SensorType type);
@@ -27,6 +25,9 @@ class PlatformSensorProviderBase : public base::NonThreadSafe {
   // Shared buffer getters.
   mojo::ScopedSharedBufferHandle CloneSharedBufferHandle();
 
+  // Gets shared buffer offset for the given sensor type.
+  uint64_t GetSharedBufferOffset(mojom::SensorType type);
+
  protected:
   PlatformSensorProviderBase();
   virtual ~PlatformSensorProviderBase();
@@ -34,8 +35,7 @@ class PlatformSensorProviderBase : public base::NonThreadSafe {
   // Method that must be implemented by platform specific classes.
   virtual scoped_refptr<PlatformSensor> CreateSensorInternal(
       mojom::SensorType type,
-      mojo::ScopedSharedBufferMapping mapping,
-      uint64_t buffer_size) = 0;
+      mojo::ScopedSharedBufferMapping mapping) = 0;
 
  private:
   friend class PlatformSensor;  // To call RemoveSensor();