Add unit test for changing priority of an SSLClientSocketPool request

New unit test checks that setting the priority of a request to an
SSLClientSocketPool layered on top of a HttpProxyClientSocketPool
passes the priority change all the way down to the transport socket
pool.

Bug: 166689
Change-Id: I4a4b00106659a65ea75689c5cea1c4e44266bb13
Reviewed-on: https://chromium-review.googlesource.com/c/1356865Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Lily Chen <chlily@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612748}

net/socket/ssl_client_socket_pool_unittest.cc

@@ -720,9 +720,46 @@ TEST_F(SSLClientSocketPoolTest, SetTransportPriorityOnInitHTTP) {
   EXPECT_EQ(HIGHEST, transport_socket_pool_.requests()[0]->priority());
 }
 
-// TODO(chlily): Test that the SSLConnectJob passes priority changes down to the
-// transport socket pool (for the HTTP_PROXY case), once change priority is
-// implemented for HttpProxyClientSocketPool.
+// Test that the SSLConnectJob passes priority changes down to the transport
+// socket pool (for the HTTP_PROXY case).
+TEST_F(SSLClientSocketPoolTest, SetSocketRequestPriorityHTTP) {
+  MockWrite writes[] = {
+      MockWrite("CONNECT host:80 HTTP/1.1\r\n"
+                "Host: host:80\r\n"
+                "Proxy-Connection: keep-alive\r\n"
+                "Proxy-Authorization: Basic Zm9vOmJhcg==\r\n\r\n"),
+  };
+  MockRead reads[] = {
+      MockRead("HTTP/1.1 200 Connection Established\r\n\r\n"),
+  };
+  StaticSocketDataProvider data(reads, writes);
+  socket_factory_.AddSocketDataProvider(&data);
+  AddAuthToCache();
+  SSLSocketDataProvider ssl(ASYNC, OK);
+  socket_factory_.AddSSLSocketDataProvider(&ssl);
+
+  CreatePool(false, true /* http proxy pool */, true /* socks pool */);
+  scoped_refptr<SSLSocketParams> params = SSLParams(ProxyServer::SCHEME_HTTP);
+
+  ClientSocketHandle handle;
+  TestCompletionCallback callback;
+  int rv = handle.Init(kGroupName, params, MEDIUM, SocketTag(),
+                       ClientSocketPool::RespectLimits::ENABLED,
+                       callback.callback(), pool_.get(), NetLogWithSource());
+  EXPECT_THAT(rv, IsError(ERR_IO_PENDING));
+  EXPECT_FALSE(handle.is_initialized());
+  EXPECT_FALSE(handle.socket());
+
+  EXPECT_EQ(MEDIUM, transport_socket_pool_.last_request_priority());
+  EXPECT_EQ(MEDIUM, transport_socket_pool_.requests()[0]->priority());
+
+  handle.SetPriority(HIGHEST);
+  EXPECT_EQ(HIGHEST, transport_socket_pool_.requests()[0]->priority());
+
+  EXPECT_THAT(callback.WaitForResult(), IsOk());
+  EXPECT_TRUE(handle.is_initialized());
+  EXPECT_TRUE(handle.socket());
+}
 
 TEST_F(SSLClientSocketPoolTest, HttpProxyBasicAsync) {
   MockWrite writes[] = {