relnote: moves ProcessPacketInterface from quic_dispatcher.h to
quic_packet_reader.h, and updates QuiClient to implement this interface.
No functional change to internal server.

add an new member function in quic client to read multiple packets per
call.

TODO: Implement in chromium to read multiple packets per call.

FIXED=21846229

Merge internal change: 101790938

relnote: N/A. Moved ProcessPacketInterface to a new file to fix
chromium build problems.

Moved ProcessPacketInterface class from quic_packet_reader.h into a
separate file that could be included by both quic_dispatcher.h and
quic_packet_reader.h.

In chromium, we build quic_packet_reader.cc on posix platform only
becuase it uses mmsghdr which is not supported on other platforms.

This fixes the problem with porting the following CL:
	101790938

Chromium cl: https://codereview.chromium.org/1640343002/

Will merge this CL into the above CL to fix IOS, mac, windows and
android compile problems.

Merge internal change: 113186932

[email protected], [email protected]

Review URL: https://codereview.chromium.org/1640343002

Cr-Commit-Position: refs/heads/master@{#372126}
9 files changed