Reduce the amount of included header files. Vast change like in "Oh God! This...

net/url_request/mime_sniffer_proxy.h

Index: net/url_request/mime_sniffer_proxy.h
===================================================================
--- net/url_request/mime_sniffer_proxy.h	(revision 9942)
+++ net/url_request/mime_sniffer_proxy.h	(working copy)
@@ -22,9 +22,12 @@
 #ifndef NET_URL_REQUEST_MIME_SNIFFER_PROXY_H_
 #define NET_URL_REQUEST_MIME_SNIFFER_PROXY_H_
 
-#include "net/base/io_buffer.h"
 #include "net/url_request/url_request.h"
 
+namespace net {
+class IOBuffer;
+}
+
 class MimeSnifferProxy : public URLRequest::Delegate {
  public:
   // The constructor inserts this MimeSnifferProxy in between the URLRequest