Fix custom cursors on Mac. Null and 0 turn out not to be opposites....

webkit/glue/webcursor_mac.mm

 // Copyright (c) 2008 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.
 
 #include "webkit/glue/webcursor.h"
 
 #import <AppKit/AppKit.h>
 
 #include "base/logging.h"
 #include "base/scoped_cftyperef.h"
@@ skipping 31 matching lines @@
                             custom_size.width()*4,
                             cg_color.get(),
                             kCGImageAlphaPremultipliedLast |
                             kCGBitmapByteOrder32Big));
   return CGBitmapContextCreateImage(context.get());
 }
 
 NSCursor* CreateCustomCursor(const std::vector<char>& custom_data,
                              const gfx::Size& custom_size,
                              const gfx::Point& hotspot) {
+  DCHECK(!custom_data.empty());

[pink (ping after 24hrs), 2009/07/09 21:30:31]

is it worth being over-protective (since this takes out the browser process
hard) and returning nil if this check fails? Can callers handle that? Is it
better than throwing a cocoa exception here in release builds?

[darin (slow to review), 2009/07/09 21:35:45]

we should only reach here if webkit tries to send us a custom cursor that has no
data.  that situation shouldn't be possible.

will our crash handler catch the cocoa exception?

return early just gimps the feature silently.  i'd much rather get a crash
report.

+
   scoped_cftyperef<CGImageRef> cg_image(
       CreateCGImageFromCustomData(custom_data, custom_size));
 
   NSBitmapImageRep* ns_bitmap =
       [[NSBitmapImageRep alloc] initWithCGImage:cg_image.get()];
   NSImage* cursor_image = [[NSImage alloc] init];
   DCHECK(cursor_image);
   [cursor_image addRepresentation:ns_bitmap];
   [ns_bitmap release];
 
@@ skipping 147 matching lines @@
   return true;
 }
 
 void WebCursor::CleanupPlatformData() {
   return;
 }
 
 void WebCursor::CopyPlatformData(const WebCursor& other) {
   return;
 }