[Mac] When the Lion gesture preferences are unset, return the intrinsic default of YES.

chrome/browser/ui/cocoa/gesture_utils.mm

 // Copyright (c) 2011 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/ui/cocoa/gesture_utils.h"
 
 #include "base/mac/mac_util.h"
 
 namespace gesture_utils {
 
@@ skipping 11 matching lines @@
   //  B) Swipe left or right with three fingers.
   //  C) Swipe with two or three fingers.
   //
   // The three-finger gesture is controlled by the integer preference
   // |com.apple.trackpad.threeFingerHorizSwipeGesture|. Its value is 0 for (A)
   // and 1 for (B, C).
   //
   // The two-finger gesture is controlled by the preference below and is boolean
   // YES for (A, C) and NO for (B).
   NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
-  return [defaults boolForKey:@"AppleEnableSwipeNavigateWithScrolls"];
+  [defaults synchronize];
+
+  // By default, the preference is not set. When it's not, the intrinsic Lion
+  // default (YES) should be returned.
+  NSDictionary* prefs = [defaults dictionaryRepresentation];
+  NSNumber* value = [prefs objectForKey:@"AppleEnableSwipeNavigateWithScrolls"];
+  if (!value)
+    return YES;
+
+  // If the preference is set, return the value.
+  return [value boolValue];
 }
 
 // On Lion, returns YES if the scroll direction is "natural"/inverted. All other
 // OSes will return NO.
 BOOL IsScrollDirectionInverted() {
   if (!base::mac::IsOSLionOrLater())
     return NO;
 
   NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
-  // The defaults must be synchronized here otherwise a stale value will be
-  // returned for an indeterminate amount of time. For some reason, this is
-  // not necessary in |-recognizeTwoFingerGestures|.
   [defaults synchronize];
-  return [defaults boolForKey:@"com.apple.swipescrolldirection"];
+
+  // By default, the preference is not set. When it's not, the intrinsic Lion
+  // default (YES) should be returned.
+  NSDictionary* prefs = [defaults dictionaryRepresentation];
+  NSNumber* value = [prefs objectForKey:@"com.apple.swipescrolldirection"];
+  if (!value)
+    return YES;
+
+  return [value boolValue];
 }
 
 }  // namespace gesture_utils