[Sync] Port about:sync to DOMUI

Write chrome://sync-internals DOMUI page which is like about:sync but
automatically updates on sync events.

Make about:sync{,-internals} aliases for chrome://sync-internals.

More diagnostic capabilities will be added to chrome://sync-internals
in future CLs.

BUG=69500
TEST=Manual

Review URL: http://codereview.chromium.org/6299002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@71435 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 68b508f..1b3bde1 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -986,6 +986,12 @@
         'browser/dom_ui/shown_sections_handler.h',
         'browser/dom_ui/slideshow_ui.cc',
         'browser/dom_ui/slideshow_ui.h',
+        'browser/dom_ui/sync_internals_html_source.cc',
+        'browser/dom_ui/sync_internals_html_source.h',
+        'browser/dom_ui/sync_internals_message_handler.cc',
+        'browser/dom_ui/sync_internals_message_handler.h',
+        'browser/dom_ui/sync_internals_ui.cc',
+        'browser/dom_ui/sync_internals_ui.h',
         'browser/dom_ui/textfields_ui.cc',
         'browser/dom_ui/textfields_ui.h',
         'browser/dom_ui/tips_handler.cc',