Clean up app_shell GN build.

extensions/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("//extensions/extensions.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 import("//tools/grit/repack.gni")
 
 assert(enable_extensions)
@@ skipping 56 matching lines @@
 
 source_set("test_support") {
   testonly = true
   sources = rebase_path(extensions_gypi_values.extensions_test_support_sources,
                         ".",
                         "//extensions")
 
   deps = [
     ":extensions_resources",
     "//base",
-    "//content/public/browser",
+    "//base:prefs_test_support",
     "//content/public/common",
     "//content/test:test_support",
     "//extensions/browser",
     "//extensions/common",
     "//extensions/common/api",
     "//extensions/common/api:api_registration",
     "//net:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 
   public_deps = [
+    "//content/public/browser",

[James Cook, 2015/02/13 21:53:31]

Question: Why does this have to be a public_dep?  (I'm not saying it shouldn't,
I just don't understand what motivates it.)

[Ken Rockot(use gerrit already), 2015/02/13 22:08:31]

Good question!

It's because one of the public headers of the test_support target (namely
extensions_test.h) exposes one of the headers of the content/public/browser
target. Without the dependency being public, targets which depend on
test_support may not receive sufficient build configuration to find that header.

That's effectively the only rule to determine choice between deps or
public_deps: if A depends on B and A's public interface exposes this dependency,
then B is a public dependency of A.

     "//extensions/common/api/cast_channel:cast_channel_proto",
   ]
 
   if (is_win) {
     cflags = [ "/wd4267" ]  # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   }
 }
 
 # GYP version: //extensions/extensions.gyp:extensions_shell_and_test_pak
 repack("shell_and_test_pak") {
@@ skipping 114 matching lines @@
   ]
 
   if (is_win) {
     deps += [ "//base/allocator" ]
   }
 
   if (is_mac) {
     deps += [ "shell:app_shell" ]  # Needed for App Shell.app's Helper.
   }
 }