Adding ArcBridge interface for synchronizing brightness settings

components/arc/common/power.mojom

Index: components/arc/common/power.mojom
diff --git a/components/arc/common/power.mojom b/components/arc/common/power.mojom
index 195c7c828e391bbe58138f3472b98c25ba54b0cf..4bff301b91b1d3c458ab2d4f163e705411637172 100644
--- a/components/arc/common/power.mojom
+++ b/components/arc/common/power.mojom
@@ -27,6 +27,12 @@ interface PowerHost {
 
   // Checks if there is a display on.
   [MinVersion=1] IsDisplayOn@2() => (bool is_on);
+
+  // Set screen brightness.

[Muyuan, 2017/04/05 18:41:08]

Same as L22

[yueli, 2017/04/05 19:59:47]

Done.

+  SetBrightness@3(int32 brightness);

[Muyuan, 2017/04/05 18:41:08]

add MinVersion

[Luis Héctor Chávez, 2017/04/05 19:14:40]

Also document the range of |brightness|. I'd rather have you send the brightness
as a percentage to avoid conversions here and do them on Android, so change this
to |double percentage|.

[yueli, 2017/04/05 19:59:46]

Done.

+
+  // Synchronize screen brightness.
+  SyncBrightness@4();

[Muyuan, 2017/04/05 18:41:10]

Same

[Luis Héctor Chávez, 2017/04/05 19:14:40]

Why is this needed? Can't you always send the initial brightness when the
Android side connects?

[victorhsieh0, 2017/04/05 19:14:51]

nit: This name is a bit ambiguous to me.  Would RequestBrightness be more clear?
 Also, would be nice to mention the instance's UpdateBrightness will be called
in the comment.

[yueli, 2017/04/05 19:59:46]

Done.

[yueli, 2017/04/05 21:19:55]

Done.

 };
 
 // Next method ID: 4
@@ -43,4 +49,7 @@ interface PowerInstance {
 
   // Called when the system has just resumed.
   [MinVersion=2] Resume@3();
+
+  // Update android brightness settings.
+  UpdateBrightness@4(int32 brightness);

[Muyuan, 2017/04/05 18:41:08]

Same as L32

[Luis Héctor Chávez, 2017/04/05 19:14:40]

Same as L32: please send the brightness as a double percentage.

[yueli, 2017/04/05 19:59:46]

Done.

 };