Remove TaskScheduler::CreateAndSetSimpleTaskScheduler().

This method has been replaced by
CreateAndStartWithDefaultParams().

TBR=gab@chromium.org
BUG=690706
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_cronet_tester

Review-Url: https://codereview.chromium.org/2836293006
Cr-Commit-Position: refs/heads/master@{#467472}
12 files changed