Add request_id to HttpRequestInfo and pass it to the NetworkDelegate for events.

net/http/http_request_info.cc

Index: net/http/http_request_info.cc
diff --git a/net/http/http_request_info.cc b/net/http/http_request_info.cc
index 8ab3096d2880e7a02fdac2c28bc00f2b6f84f34f..18c1b84fd8e317ca45823cb464012c7be2d5dfbc 100644
--- a/net/http/http_request_info.cc
+++ b/net/http/http_request_info.cc
@@ -9,7 +9,8 @@ namespace net {
 HttpRequestInfo::HttpRequestInfo()
     : load_flags(0),
       priority(LOWEST),
-      motivation(NORMAL_MOTIVATION) {
+      motivation(NORMAL_MOTIVATION),
+      request_id(0) {
 }
 
 HttpRequestInfo::~HttpRequestInfo() {}