GPU compositing on OSX canary broken

Fixes logic for USE_AURA=1 case in Mac compositor.  Changes the code to not rely on |IsOffscreen| test to determine NSView-based surface.

BUG=105036
TEST=Manual test according to bug.
R=jbates@chromium.org, kbr@chromium.org

Review URL: http://codereview.chromium.org/8620009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@111094 0039d316-1c4b-4281-b951-d872f2087c98

ui/gfx/gl/gl_context_mac.mm

@@ -42,17 +42,16 @@ scoped_refptr<GLContext> GLContext::CreateGLContext(
   switch (GetGLImplementation()) {
     case kGLImplementationDesktopGL: {
       scoped_refptr<GLContext> context;
-      if (compatible_surface->IsOffscreen()) {
-        context = new GLContextCGL(share_group);
-        if (!context->Initialize(compatible_surface, gpu_preference))
-          return NULL;
-      } else {
 #if defined(USE_AURA)
-        context = new GLContextNSView(share_group);
-        if (!context->Initialize(compatible_surface, gpu_preference))
-          return NULL;
-#endif
-      }
+      DCHECK(!compatible_surface->IsOffscreen());
+      context = new GLContextNSView(share_group);
+      if (!context->Initialize(compatible_surface, gpu_preference))
+        return NULL;
+#else
+      context = new GLContextCGL(share_group);
+      if (!context->Initialize(compatible_surface, gpu_preference))
+        return NULL;
+#endif // USE_AURA
 
       return context;
     }