Reland of Setting is_component_build to false by default

.gn

 # Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/dotfile_settings.gni")
 
@@ skipping 33 matching lines @@
   "//webrtc/modules/video_processing/*",
   "//webrtc/modules/remote_bitrate_estimator/*",
   "//webrtc/stats/*",
   "//webrtc/voice_engine/*",
 ]
 
 # These are the list of GN files that run exec_script. This whitelist exists
 # to force additional review for new uses of exec_script, which is strongly
 # discouraged except for gypi_to_gn calls.
 exec_script_whitelist = build_dotfile_settings.exec_script_whitelist
+
+default_args = {
+  # Webrtc does not support component builds because we are not using the
+  # template "component" but we rely directly on "rtc_static_library" and
+  # "rtc_shared_library". This means that we cannot use the chromium default
+  # value for this argument.
+  # This also means that the user can override this value using --args or
+  # the args.gn file but this setting will be ignored because we don't support
+  # component builds.
+  is_component_build = false
+}