Clean up a few includes, introduce iwyu.

include/core/SkRefCnt.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkRefCnt_DEFINED
 #define SkRefCnt_DEFINED
 
 #include "SkAtomics.h"
-#include "SkInstCnt.h"
+#include "SkInstCnt.h"  // IWYU pragma: export

[mtklein, 2015/06/24 22:52:01]

Does this indicate we should move the contents of SkInstCnt into this file?

[bungeman-skia, 2015/06/25 14:45:06]

Maybe? Now that we have asan and the like, is it still worth having it?

 #include "SkTemplates.h"
 
 /** \class SkRefCntBase
 
     SkRefCntBase is the base class for objects that may be shared by multiple
     objects. When an existing owner wants to share a reference, it calls ref().
     When an owner wants to release its reference, it calls unref(). When the
     shared object's reference count goes to zero as the result of an unref()
     call, its (virtual) destructor is called. It is an error for the
     destructor to be called explicitly (or via the object going out of scope on
@@ skipping 218 matching lines @@
             SkDELETE((const Derived*)this);
         }
     }
     void  deref() const { this->unref(); }
 
 private:
     mutable int32_t fRefCnt;
 };
 
 #endif