Move initCommandLine() to attachBaseContext (take 2)

* Goal is to simplify flag initialization.
  * Most code can now safely assume flags have been initialized.
* Moves isIsolatedProcess() and getProcessName() into base/.
* Disables early tracing for GPU process.
  * I don't think this is something we care about.

Bug: 789275, 789245
Change-Id: If91976d086c4f3e9dadf1798be927be3e2c3029c
Reviewed-on: https://chromium-review.googlesource.com/804215
Commit-Queue: agrieve <agrieve@chromium.org>
Reviewed-by: Stephen Lanham <slan@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533412}
30 files changed