Make ShareGroup thread safe

gpu/command_buffer/client/atomicops.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "../client/atomicops.h"
+#include "../common/logging.h"
 
 #if !defined(__native_client__)
 #include "base/atomicops.h"
+#include "base/synchronization/lock.h"
+#else
+#include <pthread.h>
 #endif
 
 namespace gpu {
 
 void MemoryBarrier() {
 #if defined(__native_client__)
   __sync_synchronize();
 #else
   base::subtle::MemoryBarrier();
 #endif
 }
 
+#if defined(__native_client__)
+
+class LockImpl {
+ public:
+  LockImpl()
+       : acquired_(false) {
+    pthread_mutex_init(&mutex_, NULL);
+  }
+
+  ~LockImpl() {
+    pthread_mutex_destroy(&mutex_);
+  }
+
+  void Acquire() {
+    pthread_mutex_lock(&mutex_);
+    acquired_ = true;
+  }
+
+  void Release() {
+    GPU_DCHECK(acquired_);
+    acquired_ = false;
+    pthread_mutex_unlock(&mutex_);
+  }
+
+  bool Try() {
+    bool acquired = pthread_mutex_trylock(&mutex_) == 0;
+    if (acquired) {
+      acquired_ = true;
+    }
+    return acquired;
+  }
+
+  void AssertAcquired() const {
+    GPU_DCHECK(acquired_);
+  }
+
+ private:
+  bool acquired_;
+  pthread_mutex_t mutex_;
+
+  DISALLOW_COPY_AND_ASSIGN(LockImpl);
+};
+
+#else  // !__native_client__
+
+class LockImpl : public base::Lock {
+};
+
+#endif  // !__native_client__
+
+Lock::Lock()
+    : lock_(new LockImpl()) {
+}
+
+Lock::~Lock() {
+}
+
+void Lock::Acquire() {
+  lock_->Acquire();
+}
+
+void Lock::Release() {
+  lock_->Release();
+}
+
+bool Lock::Try() {
+  return lock_->Try();
+}
+
+void Lock::AssertAcquired() const {
+  return lock_->AssertAcquired();
+}
+
 }  // namespace gpu