Atomics overhaul.

include/core/SkMutex.h

 #ifndef SkMutex_DEFINED
 #define SkMutex_DEFINED
 
 // This file is not part of the public Skia API.
 #include "SkTypes.h"
 
 #if defined(SK_BUILD_FOR_WIN)
     #include "../ports/SkMutex_win.h"
 #else
     #include "../ports/SkMutex_pthread.h"
 #endif
 
+class SkAutoMutexAcquire : SkNoncopyable {
+public:
+    explicit SkAutoMutexAcquire(SkBaseMutex& mutex) : fMutex(&mutex) {
+        SkASSERT(fMutex != NULL);
+        mutex.acquire();
+    }
+
+    explicit SkAutoMutexAcquire(SkBaseMutex* mutex) : fMutex(mutex) {
+        if (mutex) {
+            mutex->acquire();
+        }
+    }
+
+    /** If the mutex has not been released, release it now. */
+    ~SkAutoMutexAcquire() {
+        if (fMutex) {
+            fMutex->release();
+        }
+    }
+
+    /** If the mutex has not been released, release it now. */
+    void release() {
+        if (fMutex) {
+            fMutex->release();
+            fMutex = NULL;
+        }
+    }
+
+    /** Assert that we're holding the mutex. */
+    void assertHeld() {
+        SkASSERT(fMutex);
+        fMutex->assertHeld();
+    }
+
+private:
+    SkBaseMutex* fMutex;
+};
+#define SkAutoMutexAcquire(...) SK_REQUIRE_LOCAL_VAR(SkAutoMutexAcquire)
+
+
 #endif//SkMutex_DEFINED