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

Enable one-click signin on Linux (but not ChromeOS).

Build GTK version of one-click signin dialog.

BUG=120577
TEST=On Linux, with a clean profile, sign into GMail.  The one-click infobar should pop up, and clicking "OK, sync" should bring up the one-click dialog.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=129762

Review URL: https://chromiumcodereview.appspot.com/9874006

git-svn-id: http://src.chromium.org/svn/trunk/src/build@129773 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -368,9 +368,9 @@
           '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" and chromeos==0)', {
           'enable_one_click_signin%': 1,
         }],