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diff --git a/chromium/third_party/WebKit/Source/platform/PurgeableVector.h b/chromium/third_party/WebKit/Source/platform/PurgeableVector.h
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+/*
+ * Copyright (C) 2014 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
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * 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.
+ */
+
+#ifndef PurgeableVector_h
+#define PurgeableVector_h
+
+#include "platform/PlatformExport.h"
+#include "wtf/Forward.h"
+#include "wtf/Noncopyable.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class WebDiscardableMemory;
+
+} // namespace blink
+
+namespace WebCore {
+
+// A simple vector implementation that supports purgeable memory. The vector is
+// already locked at construction and locking uses an internal counter which
+// means that N calls to lock() must be followed by N+1 calls to unlock() to
+// actually make the vector purgeable.
+class PLATFORM_EXPORT PurgeableVector {
+    WTF_MAKE_NONCOPYABLE(PurgeableVector);
+public:
+    enum PurgeableOption {
+        NotPurgeable,
+        Purgeable,
+    };
+
+    // Clients who know in advance that they will call unlock() should construct
+    // the instance with the Purgeable option so that the instance uses
+    // discardable memory from the start and unlock() doesn't cause a memcpy().
+    PurgeableVector(PurgeableOption = Purgeable);
+
+    ~PurgeableVector();
+
+    // WARNING: This causes a memcpy() if the instance was constructed with the
+    // Purgeable hint or had its internal vector moved to discardable memory
+    // after a call to unlock().
+    void adopt(Vector<char>& other);
+
+    void append(const char* data, size_t length);
+
+    void grow(size_t);
+
+    void clear();
+
+    // The instance must be locked before calling this.
+    char* data();
+
+    size_t size() const;
+
+    // Returns whether the memory is still resident.
+    bool lock();
+
+    // WARNING: Calling unlock() on an instance that wasn't created with the
+    // Purgeable option does an extra memcpy().
+    void unlock();
+
+    bool isLocked() const;
+
+    // Note that this method should be used carefully since it may not use
+    // exponential growth internally. This means that repeated/invalid uses of
+    // it can result in O(N^2) append(). If you don't exactly know what you are
+    // doing then you should probably not call this method.
+    void reserveCapacity(size_t capacity);
+
+private:
+    enum PurgeableAllocationStrategy {
+        UseExactCapacity,
+        UseExponentialGrowth,
+    };
+
+    // Copies data from the discardable buffer to the vector and clears the
+    // discardable buffer.
+    void moveDataFromDiscardableToVector();
+
+    void clearDiscardable();
+
+    bool reservePurgeableCapacity(size_t capacity, PurgeableAllocationStrategy);
+
+    size_t adjustPurgeableCapacity(size_t capacity) const;
+
+    // Vector used when the instance is constructed without the purgeability
+    // hint or when discardable memory allocation fails.
+    // Note that there can't be data both in |m_vector| and
+    // |m_discardable|, i.e. only one of them is used at a given time.
+    Vector<char> m_vector;
+    OwnPtr<blink::WebDiscardableMemory> m_discardable;
+    size_t m_discardableCapacity;
+    size_t m_discardableSize;
+    bool m_isPurgeable;
+    int m_locksCount;
+};
+
+} // namespace WebCore
+
+#endif // PurgeableVector_h