Handle app custom icon via aura::Window property.

chrome/browser/ui/ash/launcher/chrome_launcher_controller.h

Index: chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h b/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
index 33d3ba664464dd53934b226f0a580ed9bdfb8ca7..7759b8b54f2c4be66b3a5821244998f91f6c85fc 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
@@ -148,6 +148,9 @@ class ChromeLauncherController
   void SetLauncherItemImage(const ash::ShelfID& shelf_id,
                             const gfx::ImageSkia& image);
 
+  // Updates the image for a specific shelf item image from app image loader.

[msw, 2017/06/01 19:47:28]

nit: remove "image" after "shelf item", also "the app's icon loader":
"Updates the image for a specific shelf item from the app's icon loader."

[khmel, 2017/06/01 21:55:46]

Done.

+  void UpdateLauncherItemImage(const std::string& app_id);
+
   // Notify the controller that the state of an non platform app's tabs
   // have changed,
   void UpdateAppState(content::WebContents* contents, AppState app_state);
@@ -217,8 +220,6 @@ class ChromeLauncherController
   // Controller to launch ARC apps in deferred mode.
   ArcAppDeferredLauncherController* GetArcDeferredLauncher();
 
-  AppIconLoader* GetAppIconLoaderForApp(const std::string& app_id);
-
   // Sets the shelf auto-hide and/or alignment behavior from prefs.
   void SetShelfAutoHideBehaviorFromPrefs();
   void SetShelfAlignmentFromPrefs();
@@ -378,6 +379,9 @@ class ChromeLauncherController
   // An internal helper to unpin a shelf item; this does not update prefs.
   void UnpinShelfItemInternal(const ash::ShelfID& id);
 
+  // Resolves app icon image loader for the app.

[msw, 2017/06/01 19:47:28]

nit: "the app icon"

[khmel, 2017/06/01 21:55:46]

Done.

+  AppIconLoader* GetAppIconLoaderForApp(const std::string& app_id);
+
   static ChromeLauncherController* instance_;
 
   // The currently loaded profile used for prefs and loading extensions. This is