Remove PathCloseFrame, QuicPathId, DefaultPathId and InvalidPathId.

net/quic/core/frames/quic_frame.cc

Index: net/quic/core/frames/quic_frame.cc
diff --git a/net/quic/core/frames/quic_frame.cc b/net/quic/core/frames/quic_frame.cc
index 4e086744a410c9b2f0e02778aaa62c729ddf3ada..e209b762fc73190f2b51e0020e39fd06c9ccfa6a 100644
--- a/net/quic/core/frames/quic_frame.cc
+++ b/net/quic/core/frames/quic_frame.cc
@@ -43,9 +43,6 @@ QuicFrame::QuicFrame(QuicWindowUpdateFrame* frame)
 QuicFrame::QuicFrame(QuicBlockedFrame* frame)
     : type(BLOCKED_FRAME), blocked_frame(frame) {}
 
-QuicFrame::QuicFrame(QuicPathCloseFrame* frame)
-    : type(PATH_CLOSE_FRAME), path_close_frame(frame) {}
-
 void DeleteFrames(QuicFrames* frames) {
   for (QuicFrame& frame : *frames) {
     switch (frame.type) {
@@ -78,9 +75,6 @@ void DeleteFrames(QuicFrames* frames) {
       case WINDOW_UPDATE_FRAME:
         delete frame.window_update_frame;
         break;
-      case PATH_CLOSE_FRAME:
-        delete frame.path_close_frame;
-        break;
       case NUM_FRAME_TYPES:
         DCHECK(false) << "Cannot delete type: " << frame.type;
     }
@@ -147,10 +141,6 @@ std::ostream& operator<<(std::ostream& os, const QuicFrame& frame) {
       os << "type { MTU_DISCOVERY_FRAME } ";
       break;
     }
-    case PATH_CLOSE_FRAME: {
-      os << "type { PATH_CLOSE_FRAME } " << *(frame.path_close_frame);
-      break;
-    }
     default: {
       QUIC_LOG(ERROR) << "Unknown frame type: " << frame.type;
       break;