Add delete context menu for custom wallpapers and some ui tweaks

chrome/browser/chromeos/extensions/wallpaper_private_api.h

Index: chrome/browser/chromeos/extensions/wallpaper_private_api.h
diff --git a/chrome/browser/chromeos/extensions/wallpaper_private_api.h b/chrome/browser/chromeos/extensions/wallpaper_private_api.h
index 21d0eda09a71ae41ba6f9e88abf7e77621b637b1..c7526cc493374302cdfd88b6e965e961678cfd56 100644
--- a/chrome/browser/chromeos/extensions/wallpaper_private_api.h
+++ b/chrome/browser/chromeos/extensions/wallpaper_private_api.h
@@ -137,6 +137,21 @@ class WallpaperPrivateSetWallpaperFunction : public WallpaperFunctionBase {
   base::SequencedWorkerPool::SequenceToken sequence_token_;
 };
 
+class WallpaperPrivateResetWallpaperFunction
+    : public AsyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("wallpaperPrivate.resetWallpaper",
+                             WALLPAPERPRIVATE_RESETWALLPAPER)
+
+  WallpaperPrivateResetWallpaperFunction();
+
+ protected:
+  virtual ~WallpaperPrivateResetWallpaperFunction();
+
+  // AsyncExtensionFunction overrides.
+  virtual bool RunImpl() OVERRIDE;
+};
+
 class WallpaperPrivateSetCustomWallpaperFunction
     : public WallpaperFunctionBase {
  public: