[Device Orientation] Make the return value of DeviceMotionDispatcher::LastestDeviceMotionData const

The issue 233174 was filed 4 years ago though, it hasn't been started yet. This CL makes the return
value const, then change some arguments of callers to const according to the change of return value
type.

Bug: 233174
Change-Id: Ib08dc2b7dff417bf99da5a82fc1994131fec399e
Reviewed-on: https://chromium-review.googlesource.com/821338Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung.kim@lge.com>
Cr-Commit-Position: refs/heads/master@{#524000}

third_party/WebKit/Source/modules/device_orientation/DeviceMotionDispatcher.cpp

@@ -66,7 +66,7 @@ void DeviceMotionDispatcher::DidChangeDeviceMotion(
   NotifyControllers();
 }
 
-DeviceMotionData* DeviceMotionDispatcher::LatestDeviceMotionData() {
+const DeviceMotionData* DeviceMotionDispatcher::LatestDeviceMotionData() {
   return last_device_motion_data_.Get();
 }
 

third_party/WebKit/Source/modules/device_orientation/DeviceMotionDispatcher.h

@@ -57,8 +57,7 @@ class DeviceMotionDispatcher final
   ~DeviceMotionDispatcher() override;
 
   // Note that the returned object is owned by this class.
-  // FIXME: make the return value const, see crbug.com/233174.
-  DeviceMotionData* LatestDeviceMotionData();
+  const DeviceMotionData* LatestDeviceMotionData();
 
   // Inherited from WebDeviceMotionListener.
   void DidChangeDeviceMotion(const device::MotionData&) override;

third_party/WebKit/Source/modules/device_orientation/DeviceMotionEvent.cpp

@@ -43,7 +43,7 @@ DeviceMotionEvent::DeviceMotionEvent(const AtomicString& event_type,
       device_motion_data_(DeviceMotionData::Create(initializer)) {}
 
 DeviceMotionEvent::DeviceMotionEvent(const AtomicString& event_type,
-                                     DeviceMotionData* device_motion_data)
+                                     const DeviceMotionData* device_motion_data)
     : Event(event_type, false, false),  // Can't bubble, not cancelable
       device_motion_data_(device_motion_data) {}
 

third_party/WebKit/Source/modules/device_orientation/DeviceMotionEvent.h

@@ -47,11 +47,11 @@ class DeviceMotionEvent final : public Event {
     return new DeviceMotionEvent(event_type, initializer);
   }
   static DeviceMotionEvent* Create(const AtomicString& event_type,
-                                   DeviceMotionData* device_motion_data) {
+                                   const DeviceMotionData* device_motion_data) {
     return new DeviceMotionEvent(event_type, device_motion_data);
   }
 
-  DeviceMotionData* GetDeviceMotionData() const {
+  const DeviceMotionData* GetDeviceMotionData() const {
     return device_motion_data_.Get();
   }
 
@@ -67,9 +67,9 @@ class DeviceMotionEvent final : public Event {
  private:
   DeviceMotionEvent();
   DeviceMotionEvent(const AtomicString&, const DeviceMotionEventInit&);
-  DeviceMotionEvent(const AtomicString& event_type, DeviceMotionData*);
+  DeviceMotionEvent(const AtomicString& event_type, const DeviceMotionData*);
 
-  Member<DeviceMotionData> device_motion_data_;
+  Member<const DeviceMotionData> device_motion_data_;
   Member<DeviceAcceleration> acceleration_;
   Member<DeviceAcceleration> acceleration_including_gravity_;
   Member<DeviceRotationRate> rotation_rate_;