[Sensors] Improvements in shared buffer managing

third_party/WebKit/Source/modules/sensor/SensorProxy.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 SensorProxy_h
 #define SensorProxy_h
 
+#include "device/base/synchronization/shared_memory_seqlock_buffer.h"
 #include "device/generic_sensor/public/interfaces/sensor.mojom-blink.h"
 #include "device/generic_sensor/public/interfaces/sensor_provider.mojom-blink.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "platform/Supplementable.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class SensorProviderProxy;
 
@@ skipping 32 matching lines @@
                         std::unique_ptr<Function<void(bool)>>);
   void removeConfiguration(device::mojom::blink::SensorConfigurationPtr,
                            std::unique_ptr<Function<void(bool)>>);
 
   void suspend();
   void resume();
 
   device::mojom::blink::SensorType type() const { return m_type; }
   device::mojom::blink::ReportingMode reportingMode() const { return m_mode; }
 
-  struct Reading {
-    double timestamp;
-    double reading[3];
-  };
-  static_assert(sizeof(Reading) ==
-                    device::mojom::blink::SensorInitParams::kReadBufferSize,
-                "Check reading size");
+  using Reading = device::mojom::blink::SensorReading;
 
   const Reading& reading() const { return m_reading; }
 
   const device::mojom::blink::SensorConfiguration* defaultConfig() const;
 
   // Updates internal reading from shared buffer.
   void updateInternalReading();
 
   DECLARE_VIRTUAL_TRACE();
 
@@ skipping 20 matching lines @@
   device::mojom::blink::SensorPtr m_sensor;
   device::mojom::blink::SensorConfigurationPtr m_defaultConfig;
   mojo::Binding<device::mojom::blink::SensorClient> m_clientBinding;
 
   enum State { Uninitialized, Initializing, Initialized };
   State m_state;
   mojo::ScopedSharedBufferHandle m_sharedBufferHandle;
   mojo::ScopedSharedBufferMapping m_sharedBuffer;
   Reading m_reading;
   bool m_suspended;
+  using ReadingBuffer = device::SharedMemorySeqLockBuffer<Reading>;
 };
 
 }  // namespace blink
 
 #endif  // SensorProxy_h