Respect QuicAllowed policy for new streams

net/http/http_network_session.h

Index: net/http/http_network_session.h
diff --git a/net/http/http_network_session.h b/net/http/http_network_session.h
index f45ea432d5f02a251f33f045a6cd5ff5fdcc6174..94a5243b0652f9c1c702a4b0ffa3c17dc62c98c6 100644
--- a/net/http/http_network_session.h
+++ b/net/http/http_network_session.h
@@ -68,6 +68,21 @@ class NET_EXPORT HttpNetworkSession
     : NON_EXPORTED_BASE(public base::NonThreadSafe),
       public base::MemoryCoordinatorClient {
  public:
+  // Shared Parameters - one instance of this struct is intended to be shared
+  // accross multiple HttpNetworkSessions (the default copy constructor of
+  // Params just copies the pointer to SharedParams).
+  struct NET_EXPORT SharedParams {
+    SharedParams();
+    SharedParams(const SharedParams& other);
+    ~SharedParams();
+
+    // Enables QUIC for new streams (if QUIC is enabled).
+    // If SharedParams is missing, assume true.
+    // This is intended for disabling QUIC for new streams by user policy
+    // after the net stack has been initialized.
+    bool enable_quic_for_new_streams;
+  };
+
   struct NET_EXPORT Params {
     Params();
     Params(const Params& other);
@@ -92,6 +107,12 @@ class NET_EXPORT HttpNetworkSession
     uint16_t testing_fixed_https_port;
     bool enable_tcp_fast_open_for_ssl;
 
+    // Holds parameters which can change after initialization

[mmenke, 2016/12/08 20:06:44]

This aspect seems much more important than the ownership model to me. 
RunTimeModifiableParams?  DynamicSharedParams?  VariableParams?

[pmarko, 2016/12/13 06:01:51]

Good point - I think DynamicSharedParams is a good choice because it transfers
both important aspects. Renamed.

+    // and can be shared accross multiple HttpNetworkSessions.
+    // By default, the pointer is inherited on copy.
+    // May be NULL.
+    SharedParams* shared_dynamic_params;
+
     // Use SPDY ping frames to test for connection health after idle.
     bool enable_spdy_ping_based_connection_checking;
     bool enable_http2;
@@ -195,6 +216,11 @@ class NET_EXPORT HttpNetworkSession
     // Enable HTTP/0.9 for HTTP/HTTPS on ports other than the default one for
     // each protocol.
     bool http_09_on_non_default_ports_enabled;
+
+    // Evaluates if QUIC is enabled for new streams
+    // This takes into account the general quic_enabled Params member as well
+    // as shared_params, if shared_params was set.
+    bool enable_quic_for_new_streams() const;
   };
 
   enum SocketPoolType {