Support cmd-left/right for history.

chrome/browser/cocoa/chrome_browser_window.mm

 // Copyright (c) 2009 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.
 
 #import "chrome/browser/cocoa/chrome_browser_window.h"
 
 #include "base/logging.h"
 #import "chrome/browser/cocoa/browser_window_controller.h"
+#import "chrome/browser/renderer_host/render_widget_host_view_mac.h"
 #include "chrome/browser/global_keyboard_shortcuts_mac.h"
 
+typedef int (*KeyToCommandMapper)(bool, bool, bool, int);
+
 @implementation ChromeBrowserWindow
 
-- (BOOL)performKeyEquivalent:(NSEvent*)event {
+- (BOOL)handleExtraKeyboardShortcut:(NSEvent*)event fromTable:
+    (KeyToCommandMapper)commandForKeyboardShortcut {
   // Extract info from |event|.
   NSUInteger modifers = [event modifierFlags];
   const bool cmdKey = modifers & NSCommandKeyMask;
   const bool shiftKey = modifers & NSShiftKeyMask;
   const bool cntrlKey = modifers & NSControlKeyMask;
   const int keyCode = [event keyCode];
 
-  int cmdNum = CommandForKeyboardShortcut(cmdKey, shiftKey, cntrlKey,
+  int cmdNum = commandForKeyboardShortcut(cmdKey, shiftKey, cntrlKey,
       keyCode);
 
   BrowserWindowController* controller =
       (BrowserWindowController*)[self delegate];
   // A bit of sanity.
   DCHECK([controller isKindOfClass:[BrowserWindowController class]]);
   DCHECK([controller respondsToSelector:@selector(executeCommand:)]);
 
   if (cmdNum != -1) {
     [controller executeCommand:cmdNum];
     return YES;
   }
+  return NO;
+}
 
+- (BOOL)handleExtraWindowKeyboardShortcut:(NSEvent*)event {
+  return [self handleExtraKeyboardShortcut:event
+                                 fromTable:CommandForWindowKeyboardShortcut];
+}
+
+- (BOOL)handleExtraBrowserKeyboardShortcut:(NSEvent*)event {
+  return [self handleExtraKeyboardShortcut:event
+                                 fromTable:CommandForBrowserKeyboardShortcut];
+}
+
+- (BOOL)performKeyEquivalent:(NSEvent*)event {
+  // Give the web site a chance to handle the event. If it doesn't want to
+  // handle it, it will call us back with one of the |handle*| methods above.
+  NSResponder* r = [self firstResponder];

[pink (ping after 24hrs), 2009/10/09 14:36:51]

what happens when the renderer is hung? Does that mean that these keys no longer
work? I remember discussion about how much this sucks on windows a month or so
ago.

[Nico, 2009/10/09 16:50:06]

Yes, that will work once BrowserWindowCocoa::GetCommandId() is implemented (part
of issue 15090).

What will happen (but doesn't yet) is that the rwhvmac will not send the key to
the renderer in this case.

See RenderWidgetHost::ForwardKeyboardEvent(): it calls  ShouldSendToRenderer()
to decide if it should ipc the key, which ends up calling
Browser::IsReservedAccelerator(), which returns true if the accelerator has a
command id of IDC_SELECT_NEXT_TAB etc.

So BrowserWindowCocoa::GetCommandId() only has to look at
global_keyboard_shortcuts_mac and all should be fine.

(Having said that, jam's patch seems to have problems on linux with
international keyboard layouts, so maybe it will be backed out again. Who
knows.)

+  if ([r isKindOfClass:[RenderWidgetHostViewCocoa class]])
+    return [r performKeyEquivalent:event];
+
+  // Handle per-window shortcuts like cmd-1, but do not handle browser-level
+  // shortcuts like cmd-left (else, cmd-left would do history navigation even
+  // if e.g. the Omnibox has focus).
+  if ([self handleExtraWindowKeyboardShortcut:event])
+    return YES;
   return [super performKeyEquivalent:event];
 }
 
 - (void)setShouldHideTitle:(BOOL)flag {
   shouldHideTitle_ = flag;
 }
 
 -(BOOL)_isTitleHidden {
   return shouldHideTitle_;
 }
 
 @end