Replace deprecated base::NonThreadSafe in content/renderer/media/webrtc in favor of SequenceChecker.

content/renderer/media/webrtc/peer_connection_dependency_factory.h

Index: content/renderer/media/webrtc/peer_connection_dependency_factory.h
diff --git a/content/renderer/media/webrtc/peer_connection_dependency_factory.h b/content/renderer/media/webrtc/peer_connection_dependency_factory.h
index 2701e0736d6db3deb6d887dd40c7e0d85b798259..dcf5f5ea855eaafae352a5ee078281939b8a9ea4 100644
--- a/content/renderer/media/webrtc/peer_connection_dependency_factory.h
+++ b/content/renderer/media/webrtc/peer_connection_dependency_factory.h
@@ -10,6 +10,7 @@
 #include "base/files/file.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
+#include "base/sequence_checker.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread.h"
 #include "content/common/content_export.h"
@@ -45,8 +46,7 @@ class WebRtcAudioDeviceImpl;
 
 // Object factory for RTC PeerConnections.
 class CONTENT_EXPORT PeerConnectionDependencyFactory
-    : NON_EXPORTED_BASE(base::MessageLoop::DestructionObserver),
-      NON_EXPORTED_BASE(public base::NonThreadSafe) {
+    : NON_EXPORTED_BASE(base::MessageLoop::DestructionObserver) {
  public:
   PeerConnectionDependencyFactory(
       P2PSocketDispatcher* p2p_socket_dispatcher);
@@ -154,6 +154,8 @@ class CONTENT_EXPORT PeerConnectionDependencyFactory
   base::Thread chrome_signaling_thread_;
   base::Thread chrome_worker_thread_;
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   DISALLOW_COPY_AND_ASSIGN(PeerConnectionDependencyFactory);
 };