Remove unused "method" param from QuicStreamRequest::Request().

Bug: 
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I3d94af5e54d4a989a216d79895deb9cd651f7717
Reviewed-on: https://chromium-review.googlesource.com/761339
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Yixin Wang <wangyix@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515411}
5 files changed