Remove duplicate error handling of finding browser in shared_page_state
Remove duplicate error handling of finding browser in shared_page_state

Bug: chromium:843516
Change-Id: I24dc40808893bb8733e0dfb51a5e1a5b26b1fed7
Reviewed-on: https://chromium-review.googlesource.com/1061475
Reviewed-by: Juan Antonio Navarro Pérez <1649bb5e6b9eafe026580e338065dc64ba6b80b2@chromium.org>
Commit-Queue: Ned Nguyen <8e49e083cfcfb68517585b2e78d68c2fd2b70562@google.com>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult