Remove SharedBuffer::unlock() and keep Resource's SharedBuffer always locked

third_party/WebKit/Source/platform/PurgeableVector.h

 /*
  * 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
@@ skipping 28 matching lines @@
 #include <memory>
 
 namespace base {
 class DiscardableMemory;
 }
 
 namespace blink {
 
 class WebProcessMemoryDump;
 
-// 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.
+// A simple vector implementation that supports purgeable memory.
+// TODO(hiroshige): PurgeableVector is about to be removed and some
+// functionality has already been removed https://crbug.com/603791.
 class PLATFORM_EXPORT PurgeableVector {
     DISALLOW_NEW();
     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);
 
     void onMemoryDump(const String& dumpPrefix, WebProcessMemoryDump*) const;
 
 private:
     enum PurgeableAllocationStrategy {
@@ skipping 13 matching lines @@
 
     // 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;
     std::unique_ptr<base::DiscardableMemory> m_discardable;
     size_t m_discardableCapacity;
     size_t m_discardableSize;
     bool m_isPurgeable;
-    int m_locksCount;
 };
 
 } // namespace blink
 
 #endif // PurgeableVector_h