Support cntrl-tab to switch tabs on OS X.

chrome/browser/global_keyboard_shortcuts_mac.mm

Index: chrome/browser/global_keyboard_shortcuts_mac.mm
diff --git a/chrome/browser/global_keyboard_shortcuts_mac.mm b/chrome/browser/global_keyboard_shortcuts_mac.mm
index f703232ef2f1160a32296e2a8f3f399db3734648..6b7c7faf82261927ce847b04381a5984cdf07f96 100644
--- a/chrome/browser/global_keyboard_shortcuts_mac.mm
+++ b/chrome/browser/global_keyboard_shortcuts_mac.mm
@@ -11,8 +11,10 @@ const KeyboardShortcutData* GetKeyboardShortCutTable(size_t* num_entries) {
   static const KeyboardShortcutData keyboard_shortcuts[] = {
     {true,  true,  false, 30  /* ] */,       IDC_SELECT_NEXT_TAB},
     {false, false, true,  121 /* pg down */, IDC_SELECT_NEXT_TAB},
+    {false, false, true,  48 /* tab */,      IDC_SELECT_NEXT_TAB},
     {true,  true,  false, 33  /* [ */,       IDC_SELECT_PREVIOUS_TAB},
     {false, false, true,  116 /* pg_up */,   IDC_SELECT_PREVIOUS_TAB},
+    {false, true,  true,  48 /* tab */,      IDC_SELECT_PREVIOUS_TAB},
   };
 
   *num_entries = arraysize(keyboard_shortcuts);