Fix use-before-new issue in TestCastSocket.

A reference to capturing_net_log_ was passed into the base class constructor
and used before it was fully initialized. For the derived class the initialization
of the members happens stronly after the base constructors completed.

This fixes a bug found by UBSan Vptr.

BUG=617206

Review-Url: https://codereview.chromium.org/2042493002
Cr-Commit-Position: refs/heads/master@{#397846}

extensions/browser/api/cast_channel/cast_socket_unittest.cc

@@ -185,19 +185,33 @@ class TestCastSocket : public CastSocketImpl {
         kDistantTimeoutMillis, logger, device_capabilities));
   }
 
-  explicit TestCastSocket(const net::IPEndPoint& ip_endpoint,
-                          ChannelAuthType channel_auth,
-                          int64_t timeout_ms,
-                          Logger* logger,
-                          uint64_t device_capabilities)
+  TestCastSocket(const net::IPEndPoint& ip_endpoint,
+                 ChannelAuthType channel_auth,
+                 int64_t timeout_ms,
+                 Logger* logger,
+                 uint64_t device_capabilities)
+      : TestCastSocket(ip_endpoint,
+                       channel_auth,
+                       timeout_ms,
+                       logger,
+                       new net::TestNetLog(),
+                       device_capabilities) {}
+
+  TestCastSocket(const net::IPEndPoint& ip_endpoint,
+                 ChannelAuthType channel_auth,
+                 int64_t timeout_ms,
+                 Logger* logger,
+                 net::TestNetLog* capturing_net_log,
+                 uint64_t device_capabilities)
       : CastSocketImpl("some_extension_id",
                        ip_endpoint,
                        channel_auth,
-                       &capturing_net_log_,
+                       capturing_net_log,
                        base::TimeDelta::FromMilliseconds(timeout_ms),
                        false,
                        logger,
                        device_capabilities),
+        capturing_net_log_(capturing_net_log),
         ip_(ip_endpoint),
         extract_cert_result_(true),
         verify_challenge_result_(true),
@@ -296,7 +310,7 @@ class TestCastSocket : public CastSocketImpl {
     ssl_data_->set_connect_data(*connect_data);
     // NOTE: net::MockTCPClientSocket inherits from net::SSLClientSocket !!
     return std::unique_ptr<net::SSLClientSocket>(new net::MockTCPClientSocket(
-        net::AddressList(), &capturing_net_log_, ssl_data_.get()));
+        net::AddressList(), capturing_net_log_.get(), ssl_data_.get()));
   }
 
   scoped_refptr<net::X509Certificate> ExtractPeerCert() override {
@@ -313,7 +327,7 @@ class TestCastSocket : public CastSocketImpl {
 
   base::Timer* GetTimer() override { return mock_timer_.get(); }
 
-  net::TestNetLog capturing_net_log_;
+  std::unique_ptr<net::TestNetLog> capturing_net_log_;
   net::IPEndPoint ip_;
   // Simulated connect data
   std::unique_ptr<net::MockConnect> tcp_connect_data_;