[Platform] Enable to get a partial data of SharedBuffer

third_party/WebKit/Source/platform/SharedBuffer.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 107 matching lines @@
         return getSomeDataInternal(data, position);
     }
 
     // Returns the content data into "dest" as a flat buffer. "byteLength" must
     // exactly match with size(). Returns true on success, otherwise the content
     // of "dest" is not guaranteed.
     HAS_STRICTLY_TYPED_ARG
     bool getAsBytes(void* dest, STRICTLY_TYPED_ARG(byteLength)) const
     {
         STRICT_ARG_TYPE(size_t);
-        return getAsBytesInternal(dest, byteLength);
+        if (byteLength != size())
+            return false;
+
+        return getAsBytesInternal(dest, 0, byteLength);
+    }
+
+    // Copies "byteLength" bytes from "position"-th bytes (0 origin) of the content
+    // data into "dest" as a flat buffer,
+    // Returns true on success, otherwise the content of "dest" is not guaranteed.
+    HAS_STRICTLY_TYPED_ARG
+    bool getPartAsBytes(void* dest, STRICTLY_TYPED_ARG(position), STRICTLY_TYPED_ARG(byteLength)) const
+    {
+        STRICT_ARG_TYPE(size_t);
+        return getAsBytesInternal(dest, position, byteLength);
     }
 
     // Creates an SkData and copies this SharedBuffer's contents to that
     // SkData without merging segmented buffers into a flat buffer.
     sk_sp<SkData> getAsSkData() const;
 
     // See PurgeableVector::lock().
     bool lock();
 
     // WARNING: Calling unlock() on a SharedBuffer that wasn't created with the
     // purgeability option does an extra memcpy(). Please use
     // SharedBuffer::createPurgeable() if you intend to call unlock().
     void unlock();
 
     bool isLocked() const;
 
     void onMemoryDump(const String& dumpPrefix, WebProcessMemoryDump*) const;
 
 private:
     SharedBuffer();
     explicit SharedBuffer(size_t);
     SharedBuffer(const char*, size_t);
     SharedBuffer(const unsigned char*, size_t);
     SharedBuffer(const char*, size_t, PurgeableVector::PurgeableOption);
 
     // See SharedBuffer::data().
     void mergeSegmentsIntoBuffer() const;
 
     void appendInternal(const char* data, size_t);
-    bool getAsBytesInternal(void* dest, size_t) const;
+    bool getAsBytesInternal(void* dest, size_t, size_t) const;
     size_t getSomeDataInternal(const char*& data, size_t position) const;
 
     size_t m_size;
     mutable PurgeableVector m_buffer;
     mutable Vector<char*> m_segments;
 };
 
 } // namespace blink
 
 #endif // SharedBuffer_h