[Mac] Factor out keyboard shortcut handling from ChromeEventProcessingWindow.

ui/base/cocoa/command_dispatch_delegate.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_BASE_COCOA_COMMAND_DISPATCH_DELEGATE_H_
+#define UI_BASE_COCOA_COMMAND_DISPATCH_DELEGATE_H_
+
+#import <Cocoa/Cocoa.h>
+
+// Handle routing of keyboard events.
+@protocol CommandDispatchDelegate

[tapted, 2015/07/31 03:06:50]

hm - I imagined this as a regular @interface with some logic in it -- we want to
share as much of the complex logic in CEPW as possible.

I think this needs to be

@interface CommandDispatcher

which is *owned* by the CommandDisptcherDelegate, implemented by CEPW and
NativeWidgetMacNSWindow

[jackhou1, 2015/08/04 01:03:59]

Yeah, CEPW and NativeWidgetMacNSWindow only need to implement
-defaultPerformKeyEquivalent, everything else can be shared. But, most of the
shared stuff is Chrome-specific and shouldn't live in Views. 

+
+// Handles various keyboard shortcuts hooks before and after native
+// -performKeyEquivalent. Returns YES if the event is handled.
+- (BOOL)performKeyEquivalent:(NSEvent*)event
+                      window:(NSWindow*)window
+               nativeHandler:(BOOL (^)(NSEvent*))nativePerformKeyEquivalent;
+
+// Send the event to NSApp so it can be handled natively. Ensures that the event
+// is not reposted infinitely.
+- (BOOL)redispatchKeyEvent:(NSEvent*)event window:(NSWindow*)window;
+
+// Called before a native -sendEvent. Returns NO if handling of this event

[tapted, 2015/07/31 03:06:50]

Flip condition - it's currentlt the reverse of performKeyEquivalent, which
returns `YES` when the event is handled.

[jackhou1, 2015/08/04 01:03:58]

Done.

+// should stop.
+- (BOOL)preSendEvent:(NSEvent*)event;
+
+@end
+
+#endif  // UI_BASE_COCOA_COMMAND_DISPATCH_DELEGATE_H_