[DeviceLight] Add renderer+common parts

content/common/device_sensors/device_light_messages.h

Index: content/common/device_sensors/device_light_messages.h
diff --git a/content/common/device_sensors/device_motion_messages.h b/content/common/device_sensors/device_light_messages.h
similarity index 59%
copy from content/common/device_sensors/device_motion_messages.h
copy to content/common/device_sensors/device_light_messages.h
index 4b17d1024dcdc49519ccc2b509501253789730b2..f80c180d4589034a3df5a8a55196cd9f43b74d7d 100644
--- a/content/common/device_sensors/device_motion_messages.h
+++ b/content/common/device_sensors/device_light_messages.h
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// IPC messages for device motion.
+// IPC messages for device light.
 // Multiply-included message file, hence no include guard.
 
 #include "base/memory/shared_memory.h"
@@ -10,19 +10,19 @@
 #include "ipc/ipc_param_traits.h"
 #include "ipc/ipc_platform_file.h"
 
-#define IPC_MESSAGE_START DeviceMotionMsgStart
+#define IPC_MESSAGE_START DeviceLightMsgStart
 
-// Asks the browser process to activate Device Motion sensors if necessary.
-IPC_MESSAGE_CONTROL0(DeviceMotionHostMsg_StartPolling)
+// Asks the browser process to activate Device Light sensors if necessary.
+IPC_MESSAGE_CONTROL0(DeviceLightHostMsg_StartPolling)
 
 // The browser process asynchronously returns the shared memory handle that will
 // hold the data from the hardware sensors.
-// See device_motion_hardware_buffer.h for a description of how
+// See device_light_hardware_buffer.h for a description of how
 // synchronization is handled.
-IPC_MESSAGE_CONTROL1(DeviceMotionMsg_DidStartPolling,
+IPC_MESSAGE_CONTROL1(DeviceLightMsg_DidStartPolling,
                      base::SharedMemoryHandle /* handle */)

[dcheng, 2014/06/13 17:01:34]

Why use a shared memory handle? DeviceLightData is a really small struct anyway.

[riju_, 2014/06/16 09:31:51]

I was under the impression that for infrequent updates (like 1 second interval,
e.g. geolocation) we should use just pass the data object using IPC, but the
ones that require more frequent updates (DeviceLight 5 times a second), we
should use Shared Memory. Maybe shared memory  might be a bit overkill for this
small struct, but are there any disadvantages for this approach ?

 
 // Notifies the browser process that the renderer process is not using the
-// Device Motion data anymore. The number of Starts should match the number
+// Device Light data anymore. The number of Starts should match the number
 // of Stops.
-IPC_MESSAGE_CONTROL0(DeviceMotionHostMsg_StopPolling)
+IPC_MESSAGE_CONTROL0(DeviceLightHostMsg_StopPolling)