Make leak counters thread-safe

include/core/SkPostConfig.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 SkPostConfig_DEFINED
 #define SkPostConfig_DEFINED
 
@@ skipping 102 matching lines @@
 #    define SK_CRASH() do { SkNO_RETURN_HINT(); } while (true)
 #  endif
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 /**
  * SK_ENABLE_INST_COUNT controlls printing how many reference counted objects
  * are still held on exit.
  * Defaults to 1 in DEBUG and 0 in RELEASE.
- * FIXME: currently always 0, since it fails if multiple threads run at once
- * (see skbug.com/1219 ).
  */
 #ifndef SK_ENABLE_INST_COUNT
 #  ifdef SK_DEBUG
-#    define SK_ENABLE_INST_COUNT 0
+// Only enabled for static builds, because instance counting relies on static
+// variables in functions defined in header files.
+#    define SK_ENABLE_INST_COUNT !defined(SKIA_DLL)
 #  else
 #    define SK_ENABLE_INST_COUNT 0
 #  endif
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 #ifdef SK_BUILD_FOR_WIN
 #  ifndef WIN32_LEAN_AND_MEAN
 #    define WIN32_LEAN_AND_MEAN
@@ skipping 246 matching lines @@
 
 #ifndef SK_MUTEX_PLATFORM_H
 #  if defined(SK_BUILD_FOR_WIN)
 #    define SK_MUTEX_PLATFORM_H "../../src/ports/SkMutex_win.h"
 #  else
 #    define SK_MUTEX_PLATFORM_H "../../src/ports/SkMutex_pthread.h"
 #  endif
 #endif
 
 #endif // SkPostConfig_DEFINED