Cleanup mojo Wallpaper interfaces for mash.

ash/public/interfaces/wallpaper.mojom

Index: ash/public/interfaces/wallpaper.mojom
diff --git a/ash/public/interfaces/wallpaper.mojom b/ash/public/interfaces/wallpaper.mojom
index fd04d84fa62fe584df94a00be35bd3991277ae8c..42875cd40dfeb4efffb2d9fcfc40c9088fb9dc40 100644
--- a/ash/public/interfaces/wallpaper.mojom
+++ b/ash/public/interfaces/wallpaper.mojom
@@ -12,6 +12,7 @@ enum WallpaperLayout { CENTER, CENTER_CROPPED, STRETCH, TILE, };
 // Used by Chrome to set the wallpaper displayed by ash.
 interface WallpaperController {
   SetWallpaper(skia.mojom.Bitmap? wallpaper, WallpaperLayout layout);
+  GetWallpaper() => (skia.mojom.Bitmap? wallpaper, WallpaperLayout layout);

[James Cook, 2016/10/14 21:58:02]

Document all mojom functions. In this case the most interesting bit is what it
means to receive a null bitmap.

(Also, if I'm just reading the interface it's a little odd that Chrome would
need to read back the wallpaper.)

[msw, 2016/10/17 22:22:47]

Done; documented Set and removed Get.

 };
 
 // Used by ash to trigger Chrome's wallpaper picker functionality.