[Blob] Dependencies for blob storage testing

public/platform/WebThreadSafeData.h

 /*
  * Copyright (C) 2010 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 32 matching lines @@
 class RawData;
 
 // A container for raw bytes. It is inexpensive to copy a WebThreadSafeData object.
 // It is safe to pass a WebThreadSafeData across threads!!!
 class WebThreadSafeData {
 public:
     WebThreadSafeData() { }
     ~WebThreadSafeData() { reset(); }
 
     BLINK_PLATFORM_EXPORT void assign(const WebThreadSafeData&);
+    // For testing use only.

[pdr., 2015/06/02 20:26:16]

Other than two instances in WebLayer.h, I don't see other cases where we've
exposed things in platform for testing. How are similar apis tested today?

+    BLINK_PLATFORM_EXPORT void assign(const char* data, size_t length);
+
     BLINK_PLATFORM_EXPORT void reset();
 
     BLINK_PLATFORM_EXPORT size_t size() const;
     BLINK_PLATFORM_EXPORT const char* data() const;
 
     bool isEmpty() const { return !size(); }
 
 #if INSIDE_BLINK
     BLINK_PLATFORM_EXPORT WebThreadSafeData(const WTF::PassRefPtr<RawData>&);
     BLINK_PLATFORM_EXPORT WebThreadSafeData& operator=(const WTF::PassRefPtr<RawData>&);
 #else
     operator std::string() const
     {
         size_t len = size();
         return len ? std::string(data(), len) : std::string();
     }
 #endif
 
 private:
     WebPrivatePtr<RawData> m_private;
 };
 
 } // namespace blink
 
 #endif