[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 "core/dom/DOMException.h"

[timvolodine, 2016/05/06 17:04:29]

not used?

[riju_, 2016/05/12 14:12:45]

Acknowledged.

+#include "core/dom/ExceptionCode.h"
+#include "modules/sensor/SensorReading.h"
+
+namespace blink {
+
+Sensor::~Sensor()
+{
+}
+
+Sensor::Sensor(ExecutionContext* executionContext, const SensorOptions& sensorOptions)

[timvolodine, 2016/05/06 17:04:29]

the class doesn't seem to do much at this stage.. is there code that can be put
here?

[riju_, 2016/05/12 14:12:45]

Only thing i am adding is m_sensorState(SensorState::Idle), so that when
concrete sensors are created, the state is idle by default.

+    : ActiveScriptWrappable(this)
+    , ActiveDOMObject(executionContext)
+{
+}
+

[timvolodine, 2016/05/06 17:04:29]

no state() implementation as you have in the other patch
https://codereview.chromium.org/1892083002 ?

[riju_, 2016/05/12 14:12:45]

I was adding the "state" part in the next CL, but I will put it here now.

+// Getters
+SensorReading& Sensor::reading()
+{
+    return *m_sensorReading.get();

[timvolodine, 2016/05/06 17:04:29]

I understand reading can be nullable, how is that going to be handled?

[riju_, 2016/05/12 14:12:45]

Acknowledged.

+}
+
+void Sensor::suspend()
+{

[timvolodine, 2016/05/06 17:04:29]

will these remain empty? otherwise add todo

[riju_, 2016/05/12 14:12:45]

As suggested by you
(https://codereview.chromium.org/1892083002/diff/1/third_party/WebKit/Source/m...
Line 119), 
I could add the " m_hasEventListener = false;" 
But then Sensor class should inherit PlatformEventController whose primary job
is to be a 
Base controller class for registering controllers with a dispatcher.

Concrete sensors should have their own Dispatchers, hence this design.
I am adding a comment saying they will we overriden by deriving classes.
Sounds Ok?

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

so yes, maybe Sensor should inherit from PlatformEventController? That way it
would listen to page visibility as well, and that is something we would want for
sensors I believe.

also, if these methods are empty anyway could they be removed altogether? (and
maybe keep some kind of comment)

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

Done.

+}
+
+void Sensor::resume()
+{
+}
+
+void Sensor::stop()
+{
+}
+
+bool Sensor::hasPendingActivity() const
+{
+    return false;

[timvolodine, 2016/05/06 17:04:29]

I assume this needs to be overriden in deriving classes, so maybe make it pure
virtual?

[riju_, 2016/05/12 14:12:45]

yes. removing it all together from here. In ActiveScriptWrappable,
hasPendingActivity is pure virtual, so Sensor does inherit that.

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