Merge components/usb_service into device/usb.

BUILD.gn

 # Copyright (c) 2013 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.
 
 # This is the root build file for GN. GN will start processing by loading this
 # file, and recursively load all dependencies until all dependencies are either
 # resolved or known not to exist (which will cause the build to fail). So if
 # you add a new build file, there must be some path of dependencies from this
 # file to your new one or GN won't know about it.
 
@@ skipping 18 matching lines @@
     "//chrome/renderer",
     "//chrome/service",
     "//chrome/utility",
     "//components:all_components",
     "//content",
     "//content/shell:content_shell",
     "//content/test:test_support",
     "//crypto",
     "//device/bluetooth",
     "//device/nfc",
-    "//device/usb",
     "//extensions/browser",
     "//extensions/common",
     "//extensions/common/api",
     "//extensions/renderer",
     "//gin",
     "//gpu",
     "//google_apis",
     "//google_apis/gcm",
     "//ipc",
     "//ipc/mojo",
@@ skipping 179 matching lines @@
       "//webkit/child",
     ]
   }
 
   if (use_ozone) {
     deps += [
       "//ui/ozone",
       "//ui/ozone/demo",
     ]
   }
+
+  # Non-mobile builds.
+  if (!is_android && !is_ios) {
+    deps += [
+      "//device/usb",
+    ]
+  }
 }