Change g_webrtc_logging_delegate from process-level to RenderThread-level

--single-process mode may happen crash in file of webrtc_logging.cc where code
is CHECK(!g_webrtc_logging_delegate). The orginal code is to expect there to
be only one g_webrtc_logging_delegate instance in a single render process.
g_webrtc_logging_delegate is created when a RenderThreadImpl is created.
But in --single-process model all RenderThreadImpl are created in browser
process and so g_webrtc_logging_delegate may be created many times in a single
process. Then CHECK(!g_webrtc_logging_delegate) will fail.

In this patch will change g_webrtc_logging_delegate from process-level to
RenderThread-Level. Since every render process will only keep one RenderThread.

BUG=455573

Review URL: https://codereview.chromium.org/889313003

Cr-Commit-Position: refs/heads/master@{#315131}
2 files changed