Fix chromium warnings for SdpVideoFormat.

Bug: webrtc:163
Change-Id: I29ad3c00116692f047456df7721ba636bbb2ca89
Reviewed-on: https://webrtc-review.googlesource.com/64723
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22618}

modules/video_coding/frame_buffer2.h

@@ -80,6 +80,10 @@ class FrameBuffer {
 
  private:
   struct FrameInfo {
+    FrameInfo();
+    FrameInfo(FrameInfo&&);
+    ~FrameInfo();
+
     // The maximum number of frames that can depend on this frame.
     static constexpr size_t kMaxNumDependentFrames = 8;