Makes 'Cancel' the default button for extension install/uninstall confirmatio...

chrome/browser/cocoa/extension_install_prompt.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 <Cocoa/Cocoa.h>
 
 #include <string>
 
 #include "app/l10n_util_mac.h"
 #include "app/resource_bundle.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/extensions/extension_install_ui.h"
 #include "chrome/common/extensions/extension.h"
 #include "grit/browser_resources.h"
 #include "grit/chromium_strings.h"
 #include "grit/generated_resources.h"
 #include "skia/ext/skia_utils_mac.h"
 
 class Profile;
 
 void ExtensionInstallUI::ShowExtensionInstallUIPromptImpl(
     Profile* profile, Delegate* delegate, Extension* extension, SkBitmap* icon,
     const std::wstring& warning_text, bool is_uninstall) {
   NSAlert* alert = [[[NSAlert alloc] init] autorelease];
-  [alert addButtonWithTitle:l10n_util::GetNSString(
+
+  NSButton* continueButton = [alert addButtonWithTitle:l10n_util::GetNSString(
       is_uninstall ? IDS_EXTENSION_PROMPT_UNINSTALL_BUTTON :
                      IDS_EXTENSION_PROMPT_INSTALL_BUTTON)];
-  [alert addButtonWithTitle:l10n_util::GetNSString(
+  // Clear the key equivalent (currently 'Return') because cancel is the default
+  // button.
+  [continueButton setKeyEquivalent:@""];
+
+  NSButton* cancelButton = [alert addButtonWithTitle:l10n_util::GetNSString(
       IDS_EXTENSION_PROMPT_CANCEL_BUTTON)];
+  [cancelButton setKeyEquivalent:@"\r"];
+
   [alert setMessageText:l10n_util::GetNSStringF(
        is_uninstall ? IDS_EXTENSION_UNINSTALL_PROMPT_HEADING :
                       IDS_EXTENSION_INSTALL_PROMPT_HEADING,
        UTF8ToUTF16(extension->name()))];
   [alert setInformativeText:base::SysWideToNSString(warning_text)];
   [alert setAlertStyle:NSWarningAlertStyle];
   [alert setIcon:gfx::SkBitmapToNSImage(*icon)];
 
   if ([alert runModal] == NSAlertFirstButtonReturn) {
     delegate->InstallUIProceed();
   } else {
     delegate->InstallUIAbort();
   }
 }