Plumb network stack information about existence of cached copy

net/http/http_cache.h

Index: net/http/http_cache.h
diff --git a/net/http/http_cache.h b/net/http/http_cache.h
index 9ac89aabcc61bd4eda01396074e04d7b90b67424..c78cac0557760ac1a03be979aeaec6f1f0ace988 100644
--- a/net/http/http_cache.h
+++ b/net/http/http_cache.h
@@ -195,6 +195,12 @@ class NET_EXPORT HttpCache : public HttpTransactionFactory,
   virtual HttpCache* GetCache() OVERRIDE;
   virtual HttpNetworkSession* GetSession() OVERRIDE;
 
+  // Reset the network layer to allow for browser tests that probe

[rvargas (doing something else), 2014/01/15 03:26:29]

nit: don't mention browser tests

[Randy Smith (Not in Mondays), 2014/01/15 19:14:43]

Done.

+  // network changes (e.g. host unreachable).  The old network layer is
+  // returned.  Note ownership exchange.
+  scoped_ptr<HttpTransactionFactory> SetNetworkLayerForTesting(

[rvargas (doing something else), 2014/01/15 03:26:29]

I'm wondering what do you envision for the returned network layer. That means
that I'm a little uncomfortable with giving away the old value, in part because
the use requires that no requests should be in flight when the network is
switched.

So I'm guessing that you want to create a browser, grab the cache right away and
replace the network for the lifetime of that browser.

[Randy Smith (Not in Mondays), 2014/01/15 19:14:43]

So that would work for this instance, and I'm willing to do that if you'd like. 
But the use case I had envisioned for possible/later tests was for the new
HttpTransactionFactory to act as a filter, sometimes interception
HttpTransaction creation requests, and sometimes passing them through to the
original factory.  This interface would enable that usage.

[rvargas (doing something else), 2014/01/15 19:39:45]

ah, ok. That works.

+      scoped_ptr<HttpTransactionFactory> new_network_layer);
+
  protected:
   // Disk cache entry data indices.
   enum {
@@ -381,7 +387,7 @@ class NET_EXPORT HttpCache : public HttpTransactionFactory,
 
   Mode mode_;
 
-  const scoped_ptr<HttpTransactionFactory> network_layer_;
+  scoped_ptr<HttpTransactionFactory> network_layer_;
   scoped_ptr<disk_cache::Backend> disk_cache_;
 
   // The set of active entries indexed by cache key.