[Sync] [GTK] Add GTK version of the one-click signin dialog

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 357 matching lines @@
           'file_manager_extension%': 1,
         }, {
           'file_manager_extension%': 0,
         }],
 
         # Enable WebUI TaskManager on Chrome OS or Aura.
         ['chromeos==1 or use_aura==1', {
           'webui_task_manager%': 1,
         }],
 
-        # For now one-click signin is enabled only for windows and mac
-        # since the UI is not yet complete for other platforms.
-        ['OS=="win" or OS=="mac"', {
+        # TODO(akalin): Enable this for all GTK/views platforms (except for
+        # ChromeOS).
+        ['OS=="win" or OS=="mac" or OS=="linux"', {
           'enable_one_click_signin%': 1,
         }],
 
         ['OS=="android"', {
           'proprietary_codecs%': 1,
           'enable_webrtc%': 0,
         }],
 
         # Use GPU accelerated cross process image transport by default
         # on linux builds with the Aura window manager
@@ skipping 2564 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }