Fix a memory leak on the async resource handler.

net/base/io_buffer.h

Index: net/base/io_buffer.h
===================================================================
--- net/base/io_buffer.h	(revision 9177)
+++ net/base/io_buffer.h	(working copy)
@@ -5,6 +5,7 @@
 #ifndef NET_BASE_IO_BUFFER_H_
 #define NET_BASE_IO_BUFFER_H_
 
+#include "base/logging.h"
 #include "base/ref_counted.h"
 
 namespace net {
@@ -13,7 +14,9 @@
 // easier asynchronous IO handling.
 class IOBuffer : public base::RefCountedThreadSafe<IOBuffer> {
  public:
+  IOBuffer() : data_(NULL) {}
   explicit IOBuffer(int buffer_size) {
+    DCHECK(buffer_size);
     data_ = new char[buffer_size];
   }
   explicit IOBuffer(char* buffer) : data_(buffer) {}