[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.

[tapted, 2015/08/26 03:04:49]

Should say, "If the NSWindow's firstResponder implements
CommandDispatcherTarget, it is given the first opportunity to process a command,
possibly asynchronously. If the event is not handled, the target must return the
event to the CommandDispatchingWindow via -[[event window]
redispatchKeyEvent:event].

[jackhou1, 2015/08/26 06:24:42]

Done.

+// 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

[tapted, 2015/08/26 03:04:49]

declare performKeyEquivalent:(NSvent*)

[jackhou1, 2015/08/26 06:24:42]

Done.

+
+// Implements a set of hooks into the -performKeyEquivalent flow.

[tapted, 2015/08/26 03:04:49]

perhaps more like "Provides CommandDispatcher with the means to redirect key
equivalents at different stages of event handling."

[jackhou1, 2015/08/26 06:24:43]

Done.

+@protocol CommandDispatcherDelegate<NSObject>
+- (BOOL)handledByExtensionCommand:(NSEvent*)event

[tapted, 2015/08/26 03:04:49]

nit: objc style guide says stuff in .h must have a comment

[jackhou1, 2015/08/26 06:24:42]

Done.

+                     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.

[tapted, 2015/08/26 03:04:49]

Is `RenderWidgetHostView` relevant to this part? I think we can just say
something like ~The set of methods an NSWindow subclass needs to implement to
use CommandDispatcher.

[jackhou1, 2015/08/26 06:24:43]

Done.

+// See CommandDispatcherImpl for usage.
+@protocol CommandDispatcher

[tapted, 2015/08/26 03:04:49]

I think call this `CommandDispatchingWindow` (or CommandDispatcherOwner?)

[jackhou1, 2015/08/26 06:24:42]

Done.

+- (void)setCommandDispatcherDelegate:(id<CommandDispatcherDelegate>)delegate;

[tapted, 2015/08/26 03:04:49]

Not sure if this belongs here (coming back to this)
Yeah.. does anything call this?

[jackhou1, 2015/08/26 06:24:43]

Moved to NativeWidgetMacNSWindow.

+// Sends a key event to |NSApp sendEvent:|, but also makes sure that it's not

[tapted, 2015/08/26 03:04:49]

nit: blank line before

[jackhou1, 2015/08/26 06:24:42]

Done.

+// short-circuited to the RWHV. This is used to send keyboard events to the menu

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

RHHV -> CommandDispatcherTarget

[jackhou1, 2015/08/26 06:24:42]

Done.

+// 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

[tapted, 2015/08/26 03:04:49]

nit: blank line before

[jackhou1, 2015/08/26 06:24:42]

Done.

+// CommandDispatcherImpl calls as part of its -performKeyEquivalent flow.
+- (BOOL)defaultPerformKeyEquivalent:(NSEvent*)event;
+@end
+
+// Handles dispatch of key events including redispatching an unhandled event

[tapted, 2015/08/26 03:04:49]

I think this class should be declared first in this file (forward declare
CommandDispatchingWindow and the delgate). The comment should start with a
why-this-exists kind of rationale. E.g.

// An NSWindow can create a CommandDispatcher to assist with the interception
and redirection of key equivalents in order to execute commands. Delegate
functions indicate at what stage of the event processing a command should be
triggered (e.g. <words>). If no command is triggered, the key equivalent is
allowed to propagate to the default AppKit handling for the owning window.

[jackhou1, 2015/08/26 06:24:42]

Done.

Re-wrote most of the commentary in this file, PTAL.

+// to NSApplication.
+@interface CommandDispatcherImpl : NSObject {

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

Then this can just be called `CommandDispatcher`

[jackhou1, 2015/08/26 06:24:42]

Done.

+ @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;

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

@property? (then it doesn't need a comment :p)

[jackhou1, 2015/08/26 06:24:42]

Done.

+
+// The CommandDispatcher should override -[NSResponder performKeyEquivalent:]

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

CommandDispatcher -> CommandDispatchingWindow

[jackhou1, 2015/08/26 06:24:42]

Done.

+// with this. Handles various keyboard shortcut hooks before and after native

[tapted, 2015/08/26 03:04:49]

nit: with this -> and call this instead

[jackhou1, 2015/08/26 06:24:43]

Done.

+// -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_