views::Textfield: Implement transpose editing command.

ui/views/cocoa/bridged_content_view.mm

Index: ui/views/cocoa/bridged_content_view.mm
diff --git a/ui/views/cocoa/bridged_content_view.mm b/ui/views/cocoa/bridged_content_view.mm
index 8aab6665eeab5ce360fa1776c19013a22fd11d31..457127f4e75289302393333474e55dddda1ea3a7 100644
--- a/ui/views/cocoa/bridged_content_view.mm
+++ b/ui/views/cocoa/bridged_content_view.mm
@@ -977,6 +977,15 @@ ui::KeyEvent GetCharacterEventFromNSEvent(NSEvent* event) {
       : [self moveToEndOfLineAndModifySelection:sender];
 }
 
+// Graphical Element transposition
+
+- (void)transpose:(id)sender {
+  [self handleAction:ui::TextEditCommand::TRANSPOSE
+             keyCode:ui::VKEY_T
+             domCode:ui::DomCode::US_T

[karandeepb, 2016/06/28 03:26:27]

I am not sure if giving it the Ctrl+T keycode is appropriate here. I believe the
intention behind also providing Window/Linux specific key-codes in addition to
setting the command, is to take care of commands like PageUp, which are
currently handled using OnKeyPressed. But Ctrl+T on Windows/Linux doesn't mean
transpose. Maybe we should give a dummy keycode like ui::VKEY_UNKOWN?

+          eventFlags:ui::EF_CONTROL_DOWN];
+}
+
 // Deletions.
 
 - (void)deleteForward:(id)sender {