shill: Clean up Callback80211

Make Callback80211 objects access Config80211 through the static getter
instead of via a pointer injected at instantiation time.  Stop
duplicating base::Callback objects and use method overriding to
implement the same thing.

BUG=chromium-os:36122
TEST=Unit tests

Change-Id: I73c4eb0f807240b4ea949fa70a9a3dd3954e91a0
Reviewed-on: https://gerrit.chromium.org/gerrit/37861
Reviewed-by: Wade Guthrie <wdg@chromium.org>
Tested-by: Christopher Wiley <wiley@chromium.org>
Commit-Ready: Christopher Wiley <wiley@chromium.org>
diff --git a/mock_callback80211_object.h b/mock_callback80211_object.h
index d10c6a5..8a54d0e 100644
--- a/mock_callback80211_object.h
+++ b/mock_callback80211_object.h
@@ -8,20 +8,14 @@
 #include <gmock/gmock.h>
 
 #include "shill/callback80211_object.h"
-#include "shill/config80211.h"
-
 
 namespace shill {
 
-class Config80211;
 class UserBoundNlMessage;
 
 class MockCallback80211 : public Callback80211Object {
  public:
-  Config80211::Callback &GetCallback() { return callback_; }
-
-  explicit MockCallback80211(Config80211 *config80211)
-      : Callback80211Object(config80211) {}
+  MockCallback80211() {}
   MOCK_METHOD1(Config80211MessageCallback, void(const UserBoundNlMessage &msg));
 
  private: