Move the concept of multiple route into Network

webrtc/base/network.h

Index: webrtc/base/network.h
diff --git a/webrtc/base/network.h b/webrtc/base/network.h
index 8e5c8f0fb70e196acb1bab84321f1aa63812bf96..2e93fd5037899011c5194f3a9bb8a99738649086 100644
--- a/webrtc/base/network.h
+++ b/webrtc/base/network.h
@@ -73,12 +73,20 @@ class NetworkManager {
   virtual void StopUpdating() = 0;
 
   // Returns the current list of networks available on this machine.
-  // UpdateNetworks() must be called before this method is called.
+  // StartUpdating() must be called before this method is called.
   // It makes sure that repeated calls return the same object for a
   // given network, so that quality is tracked appropriately. Does not
   // include ignored networks.
   virtual void GetNetworks(NetworkList* networks) const = 0;

[juberti1, 2015/08/13 20:45:58]

suggest that GetNetworks return a bool so that you can return false to indicate
enumeration failed (as opposed to just having zero networks)

[guoweis_webrtc, 2015/08/13 20:54:14]

Do you mean returning false here to reprenset the idea of "adapter enumeration
disabled"?

[juberti1, 2015/08/13 22:10:11]

yes, or any other sort of error occurred. The API below can be used to verify if
enumeration is disabled.

[guoweis_webrtc, 2015/08/13 22:49:36]

there are existing override in chromium which prevents me from just modifying
the signature here.

I'll add a new function 
NetworkState RetrieveNetworks(NetworkList* networks) const = 0

NetworkState is a tri state.

Sounds reasonable?

[juberti1, 2015/08/13 23:05:27]

If you have to add a new function, I suggest adding something like

enum NetworkPermissionState { STATE_UNKNOWN, STATE_ALLOWED, STATE_BLOCKED }
NetworkPermissionState GetState()

I prefer that to adding a new function that does essentially the same thing as
GetNetworks.

 
+  // When this returns true, GetNetworks will not return any networks.
+  // GetAnyAddressNetworks should be used to retrieve the any address
+  // This function should only be called after SignalNetworksChanged is
+  // first signaled.
+  virtual bool adapter_enumeration_disabled() const {

[juberti1, 2015/08/13 20:45:58]

If it's virtual, typically it won't have the all-lowercase style used for
trivial accessors.

Also, you might want to call this something like can_get_networks(), and have it
initially false, but only set it to true once SignalNetworksChanged AND adapter
enumeration is allowed. (That would allow you to make it non-virtual).

[guoweis_webrtc, 2015/08/13 20:54:14]

I think "can_get_networks" doesn't seem to convey the idea of using the
AnyAddress networks.

1. GetNetworks shouldn't be called before SignalNetworksChanged.
==> return false
2. GetNetworks will return empty if there is really no networks OR if the
adapter enumeration is disabled.

[juberti1, 2015/08/13 22:10:11]

If enumeration is disabled, can_get_networks will remain false. But maybe we
need three states: the initial state, before SignalNetworksChanged is called,
and then the disabled/enabled states.

[guoweis_webrtc, 2015/08/13 22:49:36]

I'll just use RetrieveNetworks, instead of introducing a new function here.

+    return false;
+  }
+
   // "AnyAddressNetwork" is a network which only contains single "any address"
   // IP address.  (i.e. INADDR_ANY for IPv4 or in6addr_any for IPv6). This is
   // useful as binding to such interfaces allow default routing behavior like