* Avoid "using namespace" statements, which trigger clang's -Wheader-hygiene
  warnings in jumbo builds.
* Undefine created macros at the end of source files.

BUG=chromium:746958

Change-Id: I5d25432c314437f607b0e1be22765a6764267ba6
Reviewed-on: https://chromium-review.googlesource.com/610962Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Mostyn Bramley-Moore <mostynb@opera.com>
Cr-Commit-Position: refs/heads/master@{#47347}