theme: Unbind Ctrl-Shift-Backspace in GtkUndoView.

resources/gtkrc

Index: resources/gtkrc
diff --git a/resources/gtkrc b/resources/gtkrc
index a739318c81ae9cfc030e62354addb43dfeaf5b3d..d6b5c9dfc15ae2055a4cd3184b4c76d4650fb916 100644
--- a/resources/gtkrc
+++ b/resources/gtkrc
@@ -145,7 +145,7 @@ widget "*.chromeos-options-tab" style "WhiteBackgroundStyle"
 widget "*.chromeos-options-tab*.GtkEventBox" style "WhiteBackgroundStyle"
 
 # NOTE: The keysym names in the below bindings are case-sensitive; they
-# must match the corresponding GDK #defines, e.g. GDK_slash, GDK_Delete,
+# must match the corresponding GDK #defines, e.g. GDK_slash, GDK_BackSpace,
 # etc.  (The modifier names are case-insensitive, though.)
 
 # GTK+ hardcodes Ctrl-/ to select all text, just like Ctrl-A.  Unbind it
@@ -155,10 +155,11 @@ binding "UnbindControlSlash" {
 }
 class "*" binding "UnbindControlSlash"
 
-# GtkTextView binds Ctrl-Shift-Delete to delete all text to the end of the
-# current paragraph.  We unbind it here so it can be used to open the
-# "Clear Browsing Data" dialog while the omnibox has the focus.
-binding "UnbindControlShiftDelete" {
-  unbind "<control><shift>Delete"
+# GtkTextView binds Ctrl-Shift-Backspace.  We unbind it here so it can be
+# used to open the "Clear Browsing Data" dialog while the omnibox has the
+# focus.  GtkUndoView is a custom subclass of GtkTextView used by Chrome's
+# GTK+ omnibox implementation.
+binding "UnbindControlShiftBackspace" {
+  unbind "<control><shift>BackSpace"
 }
-class "*" binding "UnbindControlShiftDelete"
+class "GtkUndoView" binding "UnbindControlShiftBackspace"