arc: Change wakeup timers implementation to adapt to new API semantics

The Chrome OS power daemon's create timers D-Bus API now implicitly deletes
any old timers registered with a tag. Consequently, this change changes
the ARC++ client's implementation to not call a delete timers call
before calling the create D-Bus API.

BUG=chromium:916044
TEST=Run unit tests.

Change-Id: I2fb07b5d417d24f6518e369f5f82b18165962506
Reviewed-on: https://chromium-review.googlesource.com/c/1493819
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Abhishek Bhardwaj <abhishekbh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636580}
5 files changed