content: Split web_drag_dest_gtk.cc into chrome/ and content/ parts.

This patch doesn't move web_drag_dest_gtk.cc into content/, but does remove all
dependencies on chrome/ code.

- Split out a delegate interface and move it 
- cross platform code from chrome/.../bookmark_node_data.cc is moved to
  ui/.../bookmark_format.h
- gtk_util.cc has some layers split into gtk_screen_utils.cc.

BUG=none
TEST=none


Review URL: http://codereview.chromium.org/8196001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@105216 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 818f0705..2b41f88 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -2265,6 +2265,10 @@
         'browser/tab_contents/thumbnail_generator.h',
         'browser/tab_contents/spelling_menu_observer.cc',
         'browser/tab_contents/spelling_menu_observer.h',
+        'browser/tab_contents/web_drag_bookmark_handler_gtk.cc',
+        'browser/tab_contents/web_drag_bookmark_handler_gtk.h',
+        'browser/tab_contents/web_drag_dest_delegate_gtk.cc',
+        'browser/tab_contents/web_drag_dest_delegate_gtk.h',
         'browser/tab_contents/web_drag_dest_gtk.cc',
         'browser/tab_contents/web_drag_dest_gtk.h',
         'browser/tab_contents/web_drag_source_win.cc',