Protect against image conversion failure in mac::FaviconForTabContents().

chrome/browser/ui/cocoa/tab_contents/favicon_util.mm

Index: chrome/browser/ui/cocoa/tab_contents/favicon_util.mm
diff --git a/chrome/browser/ui/cocoa/tab_contents/favicon_util.mm b/chrome/browser/ui/cocoa/tab_contents/favicon_util.mm
index 390b8f9e2929755a60e0ad6cc67ac3d2b2b5fc13..dd2e17e52b13c1e43bf9dba8531390d91170a661 100644
--- a/chrome/browser/ui/cocoa/tab_contents/favicon_util.mm
+++ b/chrome/browser/ui/cocoa/tab_contents/favicon_util.mm
@@ -19,8 +19,14 @@ NSImage* FaviconForTabContents(TabContents* contents) {
   // favicon.
   if (contents && contents->FaviconIsValid()) {
     CGColorSpaceRef color_space = base::mac::GetSystemColorSpace();
-    return gfx::SkBitmapToNSImageWithColorSpace(contents->GetFavicon(),
-                                                color_space);
+    NSImage* image =
+        gfx::SkBitmapToNSImageWithColorSpace(contents->GetFavicon(),
+                                             color_space);
+    // The |image| could be nil if the conversion failed. In that case, fallback
+    // to the default image.

[Scott Hess - ex-Googler, 2011/04/26 17:55:34]

AFAICT, the only way it returns nil is if skiaBitmap.isNull().  So I'm not sure
about this comment.

[Robert Sesek, 2011/04/26 18:08:51]

I wrote the comment from memory, but you're right. Updated the comment.

+    if (image) {
+      return image;
+    }

[Scott Hess - ex-Googler, 2011/04/26 17:55:34]

Is it just me, or do those {} look extraneous?

[Robert Sesek, 2011/04/26 18:08:51]

I like extraneous braces in this instance because of the weird wrapping
whitespace above and to make the scope indentation clear with the closing brace
below.

   }
 
   return app::mac::GetCachedImageWithName(@"nav.pdf");