Make compression optional in TraceUploader.

In many instances the trace data is already compressed, and the TraceCrashServiceUploader is compressing it again.

BUG=504862

Review URL: https://codereview.chromium.org/1225923003

Cr-Commit-Position: refs/heads/master@{#337828}
7 files changed