Add an async ChannelIDSource for testing.

net/quic/test_tools/crypto_test_utils.h

Index: net/quic/test_tools/crypto_test_utils.h
diff --git a/net/quic/test_tools/crypto_test_utils.h b/net/quic/test_tools/crypto_test_utils.h
index cc16d4699b627fee761a420ba1ba3ff7acbc7668..acc687944080f3122e53e36b7924cbb7adad5923 100644
--- a/net/quic/test_tools/crypto_test_utils.h
+++ b/net/quic/test_tools/crypto_test_utils.h
@@ -38,6 +38,15 @@ class PacketSavingConnection;
 
 class CryptoTestUtils {
  public:
+  // An interface for a source of tasks to run.

[Ryan Hamilton, 2014/07/09 16:54:39]

This is a very generic description. Can you add comments which explain in more
details what subclasses of this method would do? I assume it's going to do
something like MessageLoop::RunUntilIdle() or EpollServer::ExecuteCallbacks (or
whatever that's called)?

EDIT: after reading the rest of the code, my guess was totally wrong :>

[wtc, 2014/07/09 19:44:42]

Done. Added more comments. Also renamed this class "WorkSource" and the method
"DoPendingWork". I avoided "Task" or "Callback" in the names so that the names
don't suggest the use of MessageLoop or EpollServer.

+  class TaskSource {
+   public:
+    virtual ~TaskSource() {}
+
+    // Runs all pending tasks in this source.
+    virtual void RunPending() = 0;
+  };
+
   // FakeClientOptions bundles together a number of options for configuring
   // HandshakeWithFakeClient.
   struct FakeClientOptions {
@@ -50,6 +59,10 @@ class CryptoTestUtils {
     // If channel_id_enabled is true then the client will attempt to send a
     // ChannelID.
     bool channel_id_enabled;
+
+    // If channel_id_source_async is true then the client will use an async
+    // ChannelIDSource for testing. Ignored if channel_id_enabled is false.
+    bool channel_id_source_async;
   };
 
   // returns: the number of client hellos that the client sent.
@@ -69,12 +82,13 @@ class CryptoTestUtils {
       QuicConfig* config,
       QuicCryptoServerConfig* crypto_config);
 
-  // CommunicateHandshakeMessages moves messages from |a| to |b| and back until
-  // |a|'s handshake has completed.
+  // CommunicateHandshakeMessages moves messages from |a| to |b| and back and
+  // runs pending tasks in |task_source| until |a|'s handshake has completed.
   static void CommunicateHandshakeMessages(PacketSavingConnection* a_conn,
                                            QuicCryptoStream* a,
                                            PacketSavingConnection* b_conn,
-                                           QuicCryptoStream* b);
+                                           QuicCryptoStream* b,
+                                           TaskSource* task_source = NULL);
 
   // AdvanceHandshake attempts to moves messages from |a| to |b| and |b| to |a|.
   // Returns the number of messages moved.