Fix window shadows.

chrome/browser/ui/cocoa/browser_window_controller.mm

 // Copyright (c) 2012 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/browser_window_controller.h"
 
 #include <cmath>
 #include <numeric>
 
 #include "base/command_line.h"
@@ skipping 215 matching lines @@
     initializing_ = YES;
     browser_.reset(browser);
     ownsBrowser_ = ownIt;
     NSWindow* window = [self window];
     windowShim_.reset(new BrowserWindowCocoa(browser, self));
 
     // Create the bar visibility lock set; 10 is arbitrary, but should hopefully
     // be big enough to hold all locks that'll ever be needed.
     barVisibilityLocks_.reset([[NSMutableSet setWithCapacity:10] retain]);
 
-    // Sets the window to not have rounded corners, which prevents
-    // the resize control from being inset slightly and looking ugly.
-    if ([window respondsToSelector:@selector(setBottomCornerRounded:)])
+    // Set the window to not have rounded corners, which prevents the resize
+    // control from being inset slightly and looking ugly. Only bother to do
+    // this on Snow Leopard and earlier; on Lion and later all windows have
+    // rounded bottom corners, and this won't work anyway.
+    if (base::mac::IsOSSnowLeopardOrEarlier() &&
+        [window respondsToSelector:@selector(setBottomCornerRounded:)])
       [window setBottomCornerRounded:NO];
 
     // Lion will attempt to automagically save and restore the UI. This
     // functionality appears to be leaky (or at least interacts badly with our
     // architecture) and thus BrowserWindowController never gets released. This
     // prevents the browser from being able to quit <http://crbug.com/79113>.
     if ([window respondsToSelector:@selector(setRestorable:)])
       [window setRestorable:NO];
 
     // Get the windows to swish in on Lion.
@@ skipping 1954 matching lines @@
 
 - (BOOL)supportsBookmarkBar {
   return [self supportsWindowFeature:Browser::FEATURE_BOOKMARKBAR];
 }
 
 - (BOOL)isTabbedWindow {
   return browser_->is_type_tabbed();
 }
 
 @end  // @implementation BrowserWindowController(WindowType)