ExtensionDelegate to abstract extension implementation

athena/content/DEPS

Index: athena/content/DEPS
diff --git a/athena/content/DEPS b/athena/content/DEPS
index 0d15742f86c2a0ba7fa53199e21f6fe3b9f198f3..bad75d108697b98ddb097f12cd8aef865a5203d6 100644
--- a/athena/content/DEPS
+++ b/athena/content/DEPS
@@ -1,5 +1,6 @@
 include_rules = [
   "+athena/activity/public",
+  "+athena/extensions/public",
   "+athena/home/public",
   "+athena/input/public",
   "+components/renderer_context_menu",
@@ -7,7 +8,6 @@ include_rules = [
   "+content/public",
   "+extensions/browser",
   "+extensions/common",
-  "+extensions/shell/browser",
   "+ui/app_list",
   "+ui/aura",
   "+ui/gfx",
@@ -17,3 +17,10 @@ include_rules = [
   # strictly enum/POD, header-only types, and some selected common code.
   "+third_party/WebKit/public/web/WebContextMenuData.h",
 ]
+
+specific_include_rules = {
+  # Remove this once app shell uses app_window.h (crbug.com/403726)
+  "app_activity\.cc": [
+    "+extensions/shell/browser/shell_app_window.h",
+  ],
+}