Fix thread unsafe mutex initialization.

src/ports/SkMutex_pthread.h

Index: src/ports/SkMutex_pthread.h
diff --git a/src/ports/SkMutex_pthread.h b/src/ports/SkMutex_pthread.h
index 3bf3628588cd3b66b085325697fb98f61008ae2d..9aaa0612e76911f24a14f971e1b27fa787a019cd 100644
--- a/src/ports/SkMutex_pthread.h
+++ b/src/ports/SkMutex_pthread.h
@@ -89,11 +89,13 @@ private:
 #define SK_BASE_MUTEX_INIT { PTHREAD_MUTEX_INITIALIZER, SkDEBUGCODE(0) }
 
 // Using POD-style initialization prevents the generation of a static initializer.
+//
 // Without magic statics there are no thread safety guarantees on initialization
-// of local statics (even POD).
-// As a result, it is illegal to SK_DECLARE_STATIC_MUTEX in a function.
-#define SK_DECLARE_STATIC_MUTEX(name) \
-    static inline void SK_MACRO_APPEND_LINE(name)(){} \
-    static SkBaseMutex name = SK_BASE_MUTEX_INIT
+// of local statics (even POD). As a result, it is illegal to use
+// SK_DECLARE_STATIC_MUTEX in a function.
+//
+// Because SkBaseMutex is not a primitive, a static SkBaseMutex cannot be
+// initialized in a class with this macro.
+#define SK_DECLARE_STATIC_MUTEX(name) namespace {} static SkBaseMutex name = SK_BASE_MUTEX_INIT
 
 #endif