Revert "Remove SkThread.h from public API."

src/core/SkThread.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 SkThread_DEFINED
-#define SkThread_DEFINED
-
-#include "SkTypes.h"
-
-// SK_ATOMICS_PLATFORM_H must provide inline implementations for the following declarations.
-
-/** Atomically adds one to the int referenced by addr and returns the previous value.
- *  No additional memory barrier is required; this must act as a compiler barrier.
- */
-static int32_t sk_atomic_inc(int32_t* addr);
-
-/** Atomically adds inc to the int referenced by addr and returns the previous value.
- *  No additional memory barrier is required; this must act as a compiler barrier.
- */
-static int32_t sk_atomic_add(int32_t* addr, int32_t inc);
-
-/** Atomically subtracts one from the int referenced by addr and returns the previous value.
- *  This must act as a release (SL/S) memory barrier and as a compiler barrier.
- */
-static int32_t sk_atomic_dec(int32_t* addr);
-
-/** Atomic compare and set.
- *  If *addr == before, set *addr to after and return true, otherwise return false.
- *  This must act as a release (SL/S) memory barrier and as a compiler barrier.
- */
-static bool sk_atomic_cas(int32_t* addr, int32_t before, int32_t after);
-
-/** If sk_atomic_dec does not act as an acquire (L/SL) barrier,
- *  this must act as an acquire (L/SL) memory barrier and as a compiler barrier.
- */
-static void sk_membar_acquire__after_atomic_dec();
-
-/** If sk_atomic_conditional_inc does not act as an acquire (L/SL) barrier,
- *  this must act as an acquire (L/SL) memory barrier and as a compiler barrier.
- */
-static void sk_membar_acquire__after_atomic_conditional_inc();
-
-#include SK_ATOMICS_PLATFORM_H
-
-/** Atomically adds one to the int referenced by addr iff the referenced int was not 0
- *  and returns the previous value.
- *  No additional memory barrier is required; this must act as a compiler barrier.
- */
-static inline int32_t sk_atomic_conditional_inc(int32_t* addr) {
-    int32_t prev;
-    do {
-        prev = *addr;
-        if (0 == prev) {
-            break;
-        }
-    } while (!sk_atomic_cas(addr, prev, prev+1));
-    return prev;
-}
-
-/** SK_MUTEX_PLATFORM_H must provide the following (or equivalent) declarations.
-
-class SkBaseMutex {
-public:
-    void acquire();
-    void release();
-};
-
-class SkMutex : SkBaseMutex {
-public:
-    SkMutex();
-    ~SkMutex();
-};
-
-#define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name = ...
-#define SK_DECLARE_GLOBAL_MUTEX(name) SkBaseMutex name = ...
-*/
-
-#include SK_MUTEX_PLATFORM_H
-
-
-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;
-        }
-    }
-
-private:
-    SkBaseMutex* fMutex;
-};
-#define SkAutoMutexAcquire(...) SK_REQUIRE_LOCAL_VAR(SkAutoMutexAcquire)
-
-#endif