Reuse kArcIntentHelperPackageName in c/b/

Reusing kArcIntentHelperPackageName where needed. Also adding a method
to reuse such package name + a custom string appended to it, this is
AppendStringToIntentHelperPackageName.

Bug: None
Test: Build.
Change-Id: I1b9115b808533e1e5ed3339b7f3747496ca2f0c3
Reviewed-on: https://chromium-review.googlesource.com/764396
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Commit-Queue: David Jacobo <djacobo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516326}
8 files changed