[sensors]: Introduce the Generic Sensor API.

third_party/WebKit/Source/modules/sensor/Sensor.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 Sensor_h
+#define Sensor_h
+
+#include "bindings/core/v8/ActiveScriptWrappable.h"
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "core/dom/ActiveDOMObject.h"
+#include "core/dom/ContextLifecycleObserver.h"
+#include "core/frame/PlatformEventController.h"
+#include "modules/EventTargetModules.h"
+#include "modules/ModulesExport.h"
+#include "modules/sensor/SensorOptions.h"
+#include "modules/sensor/SensorState.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class ExceptionState;
+class ScriptState;
+class SensorReading;
+
+class MODULES_EXPORT Sensor
+    : public EventTargetWithInlineData
+    , public ActiveScriptWrappable
+    , public ActiveDOMObject
+    , public PlatformEventController {

[sof, 2016/06/27 09:31:00]

Where are the implementations of the pure virtual methods that
PlatformEventController declares?

+    USING_GARBAGE_COLLECTED_MIXIN(Sensor);
+    DEFINE_WRAPPERTYPEINFO();
+
+public:
+    ~Sensor() override;
+
+    void start(ScriptState*, ExceptionState&);
+    void stop(ScriptState*, ExceptionState&);
+    void updateState(SensorState);
+
+    // EventTarget implementation.
+    const AtomicString& interfaceName() const override { return EventTargetNames::Sensor; }
+    ExecutionContext* getExecutionContext() const override { return ContextLifecycleObserver::getExecutionContext(); }
+
+    // Getters
+    String state() const;
+    // TODO(riju): crbug.com/614797 .
+    SensorReading* reading() const;
+
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(error);
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(change);
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(statechange);
+
+    // ActiveDOMObject implementation.
+    void suspend() override;
+    void resume() override;
+    void stop() override;
+    bool hasPendingActivity() const override;
+
+    DECLARE_VIRTUAL_TRACE();
+
+protected:
+    Sensor(ExecutionContext*, const SensorOptions&);
+    void notifyStateChange();
+
+    SensorState m_sensorState;
+    Member<SensorReading> m_sensorReading;
+    SensorOptions m_sensorOptions;
+};
+
+} // namespace blink
+
+#endif // Sensor_h