Enhance chrome.app.window API with window background color

extensions/browser/app_window/app_window.h

Index: extensions/browser/app_window/app_window.h
diff --git a/extensions/browser/app_window/app_window.h b/extensions/browser/app_window/app_window.h
index 66fdd4c1417d283093f447fb63943f384f6577b0..b0dcdd872743e3805545424ac6557cd98f9c40b8 100644
--- a/extensions/browser/app_window/app_window.h
+++ b/extensions/browser/app_window/app_window.h
@@ -154,6 +154,7 @@ class AppWindow : public content::WebContentsDelegate,
     SkColor active_frame_color;
     SkColor inactive_frame_color;
     bool alpha_enabled;
+    SkColor background_color;
     bool is_ime_window;
 
     // The initial content/inner bounds specification (excluding any window
@@ -363,6 +364,9 @@ class AppWindow : public content::WebContentsDelegate,
   // Whether the app window wants to be alpha enabled.
   bool requested_alpha_enabled() const { return requested_alpha_enabled_; }
 
+  // Set background color.

[Reilly Grant (use Gerrit), 2017/03/10 18:39:18]

This is a getter, it cannot "set" anything.

+  SkColor backgroundColor() const { return background_color_; }
+
   // Whether the app window is created by IME extensions.
   // TODO(bshe): rename to hide_app_window_in_launcher if it is not used
   // anywhere other than app_window_launcher_controller after M45. Otherwise,
@@ -558,6 +562,9 @@ class AppWindow : public content::WebContentsDelegate,
   // Whether |alpha_enabled| was set in the CreateParams.
   bool requested_alpha_enabled_;
 
+  // Set background color

[Reilly Grant (use Gerrit), 2017/03/10 18:39:18]

As in the IDL file, please be more specific.

+  SkColor background_color_;
+
   // Whether |is_ime_window| was set in the CreateParams.
   bool is_ime_window_;