libweave: remove uses of FOR_EACH_OBSERVER

We can just use a range-based for loop on observer lists now.

BUG=b:37434548
TEST=unit tests

Change-Id: Ibd54e81c956c64134a4ea50c367ddb39da9b25f7
Reviewed-on: https://chromium-review.googlesource.com/1058140
Commit-Ready: Eric Caruso <ejcaruso@chromium.org>
Tested-by: Eric Caruso <ejcaruso@chromium.org>
Reviewed-by: Eric Caruso <ejcaruso@chromium.org>
2 files changed