[sensors]: Introduce the Generic Sensor API.

third_party/WebKit/Source/modules/sensor/Sensor.cpp

+// 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.
+
+#include "modules/sensor/Sensor.h"
+
+#include "bindings/core/v8/ScriptPromise.h"
+#include "bindings/core/v8/ScriptPromiseResolver.h"
+#include "modules/sensor/SensorReading.h"
+
+namespace blink {
+
+Sensor::~Sensor()
+{
+}
+
+Sensor::Sensor(ExecutionContext* executionContext, const SensorOptions& sensorOptions)
+    : ActiveScriptWrappable(this)
+    , ActiveDOMObject(executionContext)
+    , m_sensorState(SensorState::Idle)
+    , m_sensorOptions(sensorOptions)
+{
+}
+
+// Getters
+String Sensor::state() const
+{
+    switch (m_sensorState) {
+    case SensorState::Idle:

[timvolodine, 2016/05/17 17:44:39]

indentation

[riju_, 2016/05/20 11:20:11]

check-webkit-style does not complain
https://www.chromium.org/blink/coding-style 
A case label should line up with its switch statement. The case statement is
indented.

[timvolodine, 2016/05/24 15:30:35]

yes sorry you are correct, this should follow the blink-style

+        return "idle";
+    case SensorState::Activating:
+        return "activating";
+    case SensorState::Active:
+        return "active";
+    case SensorState::Errored:
+        return "errored";
+    }
+    ASSERT_NOT_REACHED();
+    return "idle";
+}
+
+SensorReading* Sensor::reading() const
+{
+    if (!m_sensorReading.get())
+        return nullptr;
+    return m_sensorReading.get();

[timvolodine, 2016/05/17 17:44:40]

could you just return m_sensorReading.get() here without the if above?

[riju_, 2016/05/20 11:20:11]

Done.

+}
+
+// Default implementation of these ActiveDOMObject methods is empty as
+// the derived classes from Sensor will override them.
+void Sensor::suspend()

[timvolodine, 2016/05/17 17:44:39]

if the methods inherited from ActiveDOMObject are empty here anyway why bother
overriding them?

[haraken, 2016/05/17 23:42:48]

If you don't have a plan to do something on suspend() and resume(), you don't
need to inherit from ActiveDOMObject.

In common cases, inheriting from ContextLifecycleObserver would be enough (then
you can observe contextDestroyed()).

[riju_, 2016/05/20 11:20:11]

These are not empty any more.

+{
+}
+
+void Sensor::resume()
+{
+}
+
+void Sensor::stop()
+{
+}
+
+DEFINE_TRACE(Sensor)
+{
+    ActiveDOMObject::trace(visitor);
+    EventTargetWithInlineData::trace(visitor);
+    visitor->trace(m_sensorReading);
+}
+
+} // namespace blink