Support enabling/disabling the URL request throttler via the about:net-internals page:

- Add a new tab to the about:net-internals page.
- Add a preference item to persist user's choice.
- Remove the command line switch --disable-enforced-throttling.
- Make throttling feature off by default for now.

This is 95% based on yzshen@chromium.org's patch
http://codereview.chromium.org/6286001/ which was never landed. The
changes that have been made from that patch are mostly cosmetic, apart
from updating it to match the codebase (the patch was prepared ~2
months ago) and responding to eroman@'s initial round of code review
comments.

BUG=66062
TEST=Make sure the checkbox on about:net-internals > HTTP Throttling is checked.
(1) Type in the addresss bar a URL which is expected to return 5XX.
(2) Keep clicking the "reload" button.
(3) After a few clicks, Chrome displays an error page explaining why a net::ERR_TEMPORARILY_THROTTLED error occurs.
Make sure the checkbox on about:net-internals > HTTP Throttling is unchecked.
Following step (1) and (2) described above won't result in a net::ERR_TEMPORARILY_THROTTLED error page.

Review URL: http://codereview.chromium.org/6677085

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@79455 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 5 insertions, 1 deletions

diff --git a/chrome/browser/net/net_pref_observer.h b/chrome/browser/net/net_pref_observer.h
index b5954231..a1fd2bd 100644
--- a/chrome/browser/net/net_pref_observer.h
+++ b/chrome/browser/net/net_pref_observer.h
@@ -6,6 +6,8 @@
 #define CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_
 #pragma once
 
+#include <string>
+
 #include "base/basictypes.h"
 #include "chrome/browser/prefs/pref_member.h"
 #include "content/common/notification_observer.h"
@@ -26,10 +28,12 @@ class NetPrefObserver : public NotificationObserver {
   static void RegisterPrefs(PrefService* prefs);
 
  private:
-  void ApplySettings();
+  // If |pref_name| is NULL, all monitored preferences will be applied.
+  void ApplySettings(const std::string* pref_name);
 
   BooleanPrefMember dns_prefetching_enabled_;
   BooleanPrefMember spdy_disabled_;
+  BooleanPrefMember http_throttling_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(NetPrefObserver);
 };