[Mac] Factor out keyboard shortcut handling from ChromeEventProcessingWindow.

ui/base/cocoa/command_dispatcher.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_DISPATCHER_H_
+#define UI_BASE_COCOA_COMMAND_DISPATCHER_H_
+
+#import <Cocoa/Cocoa.h>
+
+#import "base/mac/scoped_nsobject.h"
+
+// CommandDispatcherImpl will dispatch -performKeyEquivalent to this first.
+// If the event is not handled, CommandDispatcherTarget is expected to return
+// the event via -redispatchKeyEvent.
+// The Mac RenderWidgetHostView implementation conforms to this protocol.
+@protocol CommandDispatcherTarget
+@end
+
+// Implements a set of hooks into the -performKeyEquivalent flow.
+@protocol CommandDispatcherDelegate<NSObject>
+- (BOOL)handledByExtensionCommand:(NSEvent*)event
+                     isRedispatch:(BOOL)isRedispatch;
+- (BOOL)prePerformKeyEquivalent:(NSEvent*)event window:(NSWindow*)window;
+- (BOOL)postPerformKeyEquivalent:(NSEvent*)event window:(NSWindow*)window;
+@end
+
+// Interface for an NSWindow that will dispatch key events to a
+// RenderWidgetHostView and handle redispatching them if they are not handled.
+// See CommandDispatcherImpl for usage.
+@protocol CommandDispatcher

[tapted, 2015/08/18 07:22:12]

I *think* this can be merged with CommandDispatcherDelegate -- then then there's
no need for a separate delegate object (it's always the owner)

Then CommandDispatcherImpl can just be called CommandDispatcher

[jackhou1, 2015/08/25 06:31:12]

In MacViews, NativeWidgetMacNSWindow is the CommandDispatcher, but there needs
to be a separate component for Chrome-specific stuff, hence the separation.
Also, this way, we can share ChromeCommandDispatcherDelegate between Cocoa and
Views.

[tapted, 2015/08/26 03:04:48]

Ahhhhh. Yep. my plan would only work if we could inject the CEPW at
BrowserFrameMac::CreateNSWindow(), but that's not gonna work :(.

+- (void)setCommandDispatcherDelegate:(id<CommandDispatcherDelegate>)delegate;
+// Sends a key event to |NSApp sendEvent:|, but also makes sure that it's not
+// short-circuited to the RWHV. This is used to send keyboard events to the menu
+// and the cmd-` handler if a keyboard event comes back unhandled from the
+// renderer. The event must be of type |NSKeyDown|, |NSKeyUp|, or
+// |NSFlagsChanged|.
+// Returns |YES| if |event| has been handled.
+- (BOOL)redispatchKeyEvent:(NSEvent*)event;
+// Short-circuit to the default -[NSResponder performKeyEquivalent:] which
+// CommandDispatcherImpl calls as part of its -performKeyEquivalent flow.
+- (BOOL)defaultPerformKeyEquivalent:(NSEvent*)event;
+@end
+
+// Handles dispatch of key events including redispatching an unhandled event
+// to NSApplication.
+@interface CommandDispatcherImpl : NSObject {
+ @private
+  BOOL redispatchingEvent_;
+  BOOL eventHandled_;
+  NSWindow<CommandDispatcher>* owner_;  // Weak, owns us.
+  base::scoped_nsprotocol<id<CommandDispatcherDelegate>> delegate_;
+}
+
+- (id)initWithOwner:(NSWindow<CommandDispatcher>*)owner;
+
+- (void)setDelegate:(id<CommandDispatcherDelegate>)delegate;
+
+// The CommandDispatcher should override -[NSResponder performKeyEquivalent:]
+// with this. Handles various keyboard shortcut hooks before and after native
+// -performKeyEquivalent. Returns YES if the event is handled.
+- (BOOL)performKeyEquivalent:(NSEvent*)event;
+
+// The CommandDispatcher should implement -redispatchKeyEvent: with this. Send
+// the event to NSApp so it can be handled natively. Ensures that the event is
+// not reposted infinitely.
+- (BOOL)redispatchKeyEvent:(NSEvent*)event;
+
+// The CommandDispatcher should call this before a native -sendEvent. Returns
+// YES if the event is handled.
+- (BOOL)preSendEvent:(NSEvent*)event;
+
+@end
+
+#endif  // UI_BASE_COCOA_COMMAND_DISPATCHER_H_