Mixed Content: Make MixedContentChecker completely static.

Source/core/loader/FrameLoader.h

Index: Source/core/loader/FrameLoader.h
diff --git a/Source/core/loader/FrameLoader.h b/Source/core/loader/FrameLoader.h
index cd59b852947c6df7ad1f5833790a1878161746eb..2d3e8b681802553400883919049e684ac5b080e5 100644
--- a/Source/core/loader/FrameLoader.h
+++ b/Source/core/loader/FrameLoader.h
@@ -39,7 +39,6 @@
 #include "core/loader/FrameLoaderStateMachine.h"
 #include "core/loader/FrameLoaderTypes.h"
 #include "core/loader/HistoryItem.h"
-#include "core/loader/MixedContentChecker.h"
 #include "platform/Timer.h"
 #include "platform/network/ResourceRequest.h"
 #include "wtf/Forward.h"
@@ -84,7 +83,6 @@ public:
 
     LocalFrame* frame() const { return m_frame; }
 
-    MixedContentChecker* mixedContentChecker() const { return &m_mixedContentChecker; }
     ProgressTracker& progress() const { return *m_progressTracker; }
 
     // These functions start a load. All eventually call into loadWithNavigationAction() or loadInSameDocument().
@@ -227,7 +225,6 @@ private:
     // header dependencies unless performance testing proves otherwise.
     // Some of these could be lazily created for memory savings on devices.
     mutable FrameLoaderStateMachine m_stateMachine;
-    mutable MixedContentChecker m_mixedContentChecker;
 
     OwnPtr<ProgressTracker> m_progressTracker;