Add WTF::DiscardableMemory.

Source/platform/exported/Platform.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 12 matching lines @@
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "public/platform/Platform.h"
+#include "public/platform/WebDiscardableMemory.h"
+#include "wtf/Assertions.h"
+#include "wtf/Compiler.h"
+#include "wtf/DiscardableMemory.h"
+#include "wtf/OwnPtr.h"
+#include "wtf/PassOwnPtr.h"
+#include "wtf/WTFPlatform.h"
+
+using namespace WTF;
 
 namespace blink {
 
-static Platform* s_platform = 0;
+namespace {
+
+Platform* s_platform = 0;
+
+class WTFDiscardableMemoryImpl : public DiscardableMemory {
+public:
+    explicit WTFDiscardableMemoryImpl(PassOwnPtr<WebDiscardableMemory> discardableMemory)
+        : m_discardableMemory(discardableMemory)
+    { }
+
+    virtual bool lock() OVERRIDE
+    {
+        return m_discardableMemory->lock();
+    }
+
+    virtual void* data() OVERRIDE
+    {
+        return m_discardableMemory->data();
+    }
+
+    virtual void unlock() OVERRIDE
+    {
+        return m_discardableMemory->unlock();
+    }
+
+private:
+    OwnPtr<WebDiscardableMemory> m_discardableMemory;
+};
+
+// WTFPlatformImpl is nothing more than a wrapper around blink::Platform.
+class WTFPlatformImpl : public WTFPlatform {
+public:
+    virtual PassOwnPtr<DiscardableMemory> allocateAndLockDiscardableMemory(size_t bytes) OVERRIDE
+    {
+        ASSERT(s_platform);
+        OwnPtr<WebDiscardableMemory> memory(adoptPtr(s_platform->allocateAndLockDiscardableMemory(bytes)));
+        if (!memory)
+            return PassOwnPtr<DiscardableMemory>();
+
+        return adoptPtr(new WTFDiscardableMemoryImpl(memory.release()));
+    }
+};
+
+} // namespace
 
 void Platform::initialize(Platform* platform)
 {
     s_platform = platform;
+    WTFPlatform::setInstance(new WTFPlatformImpl());
 }
 
 void Platform::shutdown()
 {
     s_platform = 0;
 }
 
 Platform* Platform::current()
 {
     return s_platform;
 }
 
 } // namespace blink