Add chrome/browser/apps/BUILD.gn and move Chrome-specific code there

chrome/browser/ui/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/chromecast_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 3352 matching lines @@
     ]
   }
   if (!is_android) {
     deps += [
       "//third_party/libaddressinput",
       "//third_party/libaddressinput:strings",
     ]
   }
   if (enable_extensions) {
     deps += [
+      "//chrome/browser/apps",
       "//chrome/browser/extensions",
       "//chrome/common/extensions/api",
       "//chrome/common/extensions/api:api_registration",
     ]
-    allow_circular_includes_from += [ "//chrome/browser/extensions" ]
+    allow_circular_includes_from += [
+      "//chrome/browser/apps",
+      "//chrome/browser/extensions",
+    ]
     sources += [
       "extensions/accelerator_priority.cc",
       "extensions/accelerator_priority.h",
       "extensions/app_launch_params.cc",
       "extensions/app_launch_params.h",
       "extensions/application_launch.cc",
       "extensions/application_launch.h",
       "extensions/blocked_action_bubble_delegate.cc",
       "extensions/blocked_action_bubble_delegate.h",
       "extensions/extension_action_platform_delegate.h",
@@ skipping 177 matching lines @@
       "test/test_confirm_bubble_model.cc",
       "test/test_confirm_bubble_model.h",
     ]
     deps += [ "//chrome/test:test_support_ui" ]
   }
 
   if (enable_extensions) {
     deps += [ "//extensions/browser" ]
   }
 }