[Sensors] Improvements in fetching reading for sensors with continuous reporting mode

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 "core/dom/ExceptionCode.h"
+#include "core/page/PageVisibilityObserver.h"
 #include "device/generic_sensor/public/cpp/sensor_reading.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/Timer.h"
 #include "platform/heap/Handle.h"
+#include "wtf/Vector.h"
 
 namespace blink {
 
 class SensorProviderProxy;
 class SensorReading;
 class SensorReadingFactory;
 
 // This class wraps 'Sensor' mojo interface and used by multiple
 // JS sensor instances of the same type (within a single frame).
 class SensorProxy final : public GarbageCollectedFinalized<SensorProxy>,
-                          public device::mojom::blink::SensorClient {
+                          public device::mojom::blink::SensorClient,
+                          public PageVisibilityObserver {
+  USING_GARBAGE_COLLECTED_MIXIN(SensorProxy);
   USING_PRE_FINALIZER(SensorProxy, dispose);
   WTF_MAKE_NONCOPYABLE(SensorProxy);
 
  public:
   class Observer : public GarbageCollectedMixin {
    public:
     // Has valid 'Sensor' binding, {add, remove}Configuration()
     // methods can be called.
     virtual void onSensorInitialized() {}
-    // Platfrom sensort reading has changed (for 'ONCHANGE' reporting mode).
+    // Platfrom sensort reading has changed.
     virtual void onSensorReadingChanged() {}
     // An error has occurred.
     virtual void onSensorError(ExceptionCode,
                                const String& sanitizedMessage,
                                const String& unsanitizedMessage) {}
+    // Sensor reading change notification is suspended.
+    virtual void onSuspended() {}
   };
 
   ~SensorProxy();
 
   void dispose();
 
   void addObserver(Observer*);
   void removeObserver(Observer*);
 
   void initialize();
 
   bool isInitializing() const { return m_state == Initializing; }
   bool isInitialized() const { return m_state == Initialized; }
 
   void addConfiguration(device::mojom::blink::SensorConfigurationPtr,
                         std::unique_ptr<Function<void(bool)>>);
-  void removeConfiguration(device::mojom::blink::SensorConfigurationPtr,
-                           std::unique_ptr<Function<void(bool)>>);
+
+  void removeConfiguration(device::mojom::blink::SensorConfigurationPtr);
 
   void suspend();
   void resume();
 
   device::mojom::blink::SensorType type() const { return m_type; }
   device::mojom::blink::ReportingMode reportingMode() const { return m_mode; }
 
   // The |SensorReading| instance which is shared between sensor instances
   // of the same type.
   // Note: the returned value is reset after updateSensorReading() call.
   SensorReading* sensorReading() const { return m_reading; }
 
   const device::mojom::blink::SensorConfiguration* defaultConfig() const;
 
   double maximumFrequency() const { return m_maximumFrequency; }
 
-  // Updates sensor reading from shared buffer.
-  void updateSensorReading();
-
   DECLARE_VIRTUAL_TRACE();
 
  private:
   friend class SensorProviderProxy;
   SensorProxy(device::mojom::blink::SensorType,
               SensorProviderProxy*,
+              Page*,
               std::unique_ptr<SensorReadingFactory>);
+  // Returns true if this instance is using polling timer to
+  // periodically fetch reading data from shared buffer.
+  bool usesPollingTimer() const;
+
+  // Updates sensor reading from shared buffer.
+  void updateSensorReading();
 
   // device::mojom::blink::SensorClient overrides.
   void RaiseError() override;
   void SensorReadingChanged() override;
 
+  // PageVisibilityObserver overrides.
+  void pageVisibilityChanged() override;
+
   // Generic handler for a fatal error.
   // String parameters are intentionally copied.
   void handleSensorError(ExceptionCode = UnknownError,
                          String sanitizedMessage = String(),
                          String unsanitizedMessage = String());
-
+  // mojo call callbacks.
   void onSensorCreated(device::mojom::blink::SensorInitParamsPtr,
                        device::mojom::blink::SensorClientRequest);
+  void onAddConfigurationCompleted(
+      double frequency,
+      std::unique_ptr<Function<void(bool)>> callback,
+      bool result);
+  void onRemoveConfigurationCompleted(double frequency, bool result);
 
   bool tryReadFromBuffer(device::SensorReading& result);
+  void updatePollingStatus();
+  void onTimerFired(TimerBase*);
 
   device::mojom::blink::SensorType m_type;
   device::mojom::blink::ReportingMode m_mode;
   Member<SensorProviderProxy> m_provider;
   using ObserversSet = HeapHashSet<WeakMember<Observer>>;
   ObserversSet m_observers;
 
   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;
   bool m_suspended;
   Member<SensorReading> m_reading;
   std::unique_ptr<SensorReadingFactory> m_readingFactory;
   double m_maximumFrequency;
 
+  // Used for continious reporting mode.
+  Timer<SensorProxy> m_timer;
+  WTF::Vector<double> m_frequenciesUsed;
+
   using ReadingBuffer = device::SensorReadingSharedBuffer;
   static_assert(
       sizeof(ReadingBuffer) ==
           device::mojom::blink::SensorInitParams::kReadBufferSizeForTests,
       "Check reading buffer size for tests");
 };
 
 }  // namespace blink
 
 #endif  // SensorProxy_h