Reverts a commit that caused ASAN failures, and 2 dependent commits.

net/disk_cache/mem_entry_impl.h

Index: net/disk_cache/mem_entry_impl.h
diff --git a/net/disk_cache/mem_entry_impl.h b/net/disk_cache/mem_entry_impl.h
index 29671547a43aeda3174596fa8b9308a230787c39..b1d47035baa8f41b5c85ffe90562c4d8886554d6 100644
--- a/net/disk_cache/mem_entry_impl.h
+++ b/net/disk_cache/mem_entry_impl.h
@@ -101,15 +101,9 @@ class MemEntryImpl : public Entry {
   virtual int ReadData(
       int index, int offset, net::IOBuffer* buf, int buf_len,
       net::OldCompletionCallback* completion_callback) OVERRIDE;
-  virtual int ReadData(
-      int index, int offset, net::IOBuffer* buf, int buf_len,
-      const net::CompletionCallback& completion_callback) OVERRIDE;
   virtual int WriteData(int index, int offset, net::IOBuffer* buf, int buf_len,
                         net::OldCompletionCallback* completion_callback,
                         bool truncate) OVERRIDE;
-  virtual int WriteData(int index, int offset, net::IOBuffer* buf, int buf_len,
-                        const net::CompletionCallback& completion_callback,
-                        bool truncate) OVERRIDE;
   virtual int ReadSparseData(
       int64 offset, net::IOBuffer* buf, int buf_len,
       net::OldCompletionCallback* completion_callback) OVERRIDE;