Don't throttle unless origin schema is chrome-extension.

BUG=83775


Review URL: http://codereview.chromium.org/9819001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@128196 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/net_internals/http_throttling_view.html

 <div id=http-throttling-view-tab-content class=content-box>
   <p>
   In order to prevent Distributed Denial of Service (DDoS) attacks from
-  being perpetrated by web pages and extensions that run within Chrome, the
+  being perpetrated by web pages or extensions that run within Chrome, the
   HTTP throttling mechanism keeps track of errors requesting a given URL
   (minus the query parameters), and after a few 5xx errors in a row, starts
   exponentially increasing an interval during which requests to the
   given URL are disallowed.
   </p><p>
-  You may enable or disable the feature below.  Please let us know if the
-  feature is causing problems for your web site.  More details and contact
-  information at 
+  This feature is currently configured to affect only requests
+  initiated by origins with one of the following schemas:
+  <ul>
+    <li> chrome-extension:// </li>
+  </ul>
+  </p><p>
+  The feature is on by default (for requests originating from the
+  schemas listed above). You may disable the feature below if desired.
+  Please let us know if the feature is causing problems for your web
+  site.  More details and contact information at
   <a href="http://dev.chromium.org/throttling" target=_blank>http://dev.chromium.org/throttling</a>.
   </p>
   <p><input id=http-throttling-view-enable-checkbox type=checkbox />

net/url_request/url_request_http_job.cc

@@ -320,7 +320,13 @@ void URLRequestHttpJob::StartTransactionInternal() {
     rv = request_->context()->http_transaction_factory()->CreateTransaction(
         &transaction_);
     if (rv == OK) {
+      // TODO(joi): The hard-coded check for "chrome-extension" is
+      // temporary (as of 2012/3/21), intended only to make sure this
+      // change (to throttle only requests originating from
+      // extensions) gets into M19. Right after the M19 branch point,
+      // I will sort this out in a more architecturally-sound way.
       if (!URLRequestThrottlerManager::GetInstance()->enforce_throttling() ||
+          request_->first_party_for_cookies().scheme() != "chrome-extension" ||
           !throttling_entry_->ShouldRejectRequest(request_info_.load_flags)) {
         rv = transaction_->Start(
             &request_info_, start_callback_, request_->net_log());