GitLab

Adds a new member variable to the `CastMetricsServiceClient`,
rather than reinitializing the `CastSysInfo` object each time
the `GetChannel()` method is called.

Bug: 145136478
Change-Id: I04cdc10ecbb7ff6761a24cedd4ab88e8098913c8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2123508Reviewed-by: Alex Sakhartchouk <alexst@chromium.org>
Commit-Queue: Aaron Knobloch <aknobloch@google.com>
Cr-Commit-Position: refs/heads/master@{#759784}