Merge change 24643 into eclair

public:

    SharedBufferStack();

    void init(int32_t identity);

    status_t setDirtyRegion(int buffer, const Region& reg);

    Region getDirtyRegion(int buffer) const;

    status_t validate(size_t token) const;

    uint32_t getIdentity(size_t token) const;

    status_t setIdentity(size_t token, uint32_t identity);

private:

    friend class SharedBufferBase;

class SharedBufferServer : public SharedBufferBase

{

public:

    SharedBufferServer(SharedClient* sharedClient, int surface, int num);

    SharedBufferServer(SharedClient* sharedClient, int surface, int num,

            int32_t identity);

    ssize_t retireAndLock();

    status_t unlock(int buffer);