Add an opt-out header for HTTP throttling. Never throttle for localhost.

net/url_request/url_request_http_job.cc

Index: net/url_request/url_request_http_job.cc
diff --git a/net/url_request/url_request_http_job.cc b/net/url_request/url_request_http_job.cc
index faf8d8407a6b061b32302f1a211b890749b82a33..e25477b6a486e9cac8500fd1039d8692d7f105a6 100644
--- a/net/url_request/url_request_http_job.cc
+++ b/net/url_request/url_request_http_job.cc
@@ -159,7 +159,8 @@ void URLRequestHttpJob::NotifyHeadersComplete() {
   if (!is_cached_content_) {
     URLRequestThrottlerHeaderAdapter response_adapter(
         response_info_->headers);
-    throttling_entry_->UpdateWithResponse(&response_adapter);
+    throttling_entry_->UpdateWithResponse(request_info_.url.host(),

[yzshen1, 2011/03/18 22:49:51]

A throttling entry is used for a specific URL (and therefore, a specific host).
I think we could avoid passing in the host for each UpdateWithResponse call.
Instead, we can do it when the throttling entry is initialized.
What do you think?

[Jói, 2011/03/23 23:38:24]

Storing the host would increase the required storage, since it is not what we
use as a key for url_entries_.  On the other hand, just creating a GURL object
parses the spec of the URL, and this is already done when the HttpRequestInfo
structure is initialized, so passing the host as a parameter should be very
cheap.

[yzshen1, 2011/03/24 20:06:37]

Okay.

On 2011/03/23 23:38:24, Jói wrote:

+                                          &response_adapter);
   }
 
   ProcessStrictTransportSecurityHeader();