Adds a NetworkChangeNotifier dependency to ProxyService; when we observer a n...

Adds a NetworkChangeNotifier dependency to ProxyService; when we observer a network change through the notifier, the ProxyService re-configures itself.

So for example, if you were to switch to VPN and are using a custom PAC URL, we will re-download that URL on the new network.
Similarly if you are using auto-detect PAC settings, we will re-run the autodiscovery steps for the next resolve.

Note that Chromium is still passing a NULL NetworkChangeNotifier dependency into its ProxyService -- until it passes a real implementation, this will not impact Chrome.

BUG=12293
TEST=ProxyServiceTest.NetworkChangeTriggersPacRefetch

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=35772

[willchan no longer on Chromium, 2010-01-08 02:42:02]

LGTM

http://codereview.chromium.org/525104/diff/12/14
File net/proxy/proxy_service.h (right):

http://codereview.chromium.org/525104/diff/12/14#newcode251
net/proxy/proxy_service.h:251: virtual void OnIPAddressChanged();
Shouldn't this be in the public section?

[eroman, 2010-01-08 03:26:33]

http://codereview.chromium.org/525104/diff/12/14
File net/proxy/proxy_service.h (right):

http://codereview.chromium.org/525104/diff/12/14#newcode251
net/proxy/proxy_service.h:251: virtual void OnIPAddressChanged();
On 2010/01/08 02:42:02, willchan wrote:
> Shouldn't this be in the public section?

I did a random sampling of other chrome codes, and found they favored putting
such implementation in the private section.

I like that style, since it helps conceal the implementation details a bit
(caller would need to cast to gain access to it).

Here are the samples I consulted (implementors of NotificationObserver):

  chrome/browser/autocomplete/autocomplete_popup_model.h
  chrome/browser/browsing_data_remover.h
  chrome/browser/extensions/user_script_listener.h

My sampling also included a counter example, so I guess our code uses both
styles:

  chrome/browser/cocoa/browser_window_cocoa.h