Remove problematic GrContext thread local instance counting

R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/104893002

git-svn-id: http://skia.googlecode.com/svn/trunk/include@12485 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/GrContext.h b/gpu/GrContext.h
index 03665d7..1770fa6 100644
--- a/gpu/GrContext.h
+++ b/gpu/GrContext.h
@@ -50,11 +50,6 @@
      */
     static GrContext* Create(GrBackend, GrBackendContext);
 
-    /**
-     * Returns the number of GrContext instances for the current thread.
-     */
-    static int GetThreadInstanceCount();
-
     virtual ~GrContext();
 
     /**