Move some component's GN build files to main tree.

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.
 
 # In GN, a "group" is a dummy target that just lists other targets.
 group("root") {
   # Note that some dependencies are commented out. These are things that are
   # currently written but not hooked up to the build yet. They may need to be
   # completed or possibly just tested and then re-enabled.
   deps = [
     # This is a temporary test of the not-yet-complete NaCl cross-compilation.
     #"//base(//build/toolchain/nacl:x86_newlib)",
 
     #"//chrome",
-    #"//components/language_usage_metrics",
-    #"//components/navigation_metrics",
-    #"//components/onc:onc_component",
-    #"//components/startup_metric_utils",
+    "//components/language_usage_metrics",
+    "//components/navigation_metrics",
+    "//components/onc",
+    "//components/startup_metric_utils",
     #"//components/translate:translate_core_browser",
     #"//components/translate:translate_core_common",
     #"//crypto",
     #"//device/usb:device_usb",
     #"//ipc",
     #"//net",
     #"//net/third_party/nss:ssl",
     #"//sdch",
     "//third_party/re2",
     #"//third_party/WebKit/Source/platform",
     #"//third_party/icu:icudata",
     #"//third_party/leveldatabase",
     #"//third_party/libpng",
     #"//third_party/zlib",
     #"//skia",
     "//tools/gn",
-    #"//url",
+    "//url",
   ]
 }