[Blink] Shuffle code to remove duplicate console message logic

WebConsoleMessage::LogWebConsoleMessage() and
WebLocalFrameImpl::AddMessageToConsole() used a fair amount of the same
code, as both were mutating a WebConsoleMessage into a ConsoleMessage,
and then logging it.

Restructure this by adding a ConsoleMessage::FromWebConsoleMessage()
method that can be used by both WebConsoleMessage and WebLocalFrameImpl.

Bug: None
Change-Id: I7a0ff42411f5e950452c86ecde7e58bb4976d7ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1501497
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637981}
4 files changed