Navigation Predictor: Merge two features into a single one

Currently, navigation predictor code defines two features:
kRecordAnchorMetricsClicked and kRecordAnchorMetricsVisible.
The original plan was to have two features to be used to
independently control two different behaviors of Chrome:
(i) UMA recording of metrics of the clicked anchor element
(ii) UMA recording of metrics of the visible anchor element.
However, we never got around to doing so, and actually used the
same feature to control all the behavior.

This CL merges the two features into a single one to make
code cleaner and simpler to understand. There is no functional
change.

Change-Id: Icedd78c9af50c0f2f76350d20d5af4bb13a7ca0d
Bug: 908725
Reviewed-on: https://chromium-review.googlesource.com/c/1416153
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Doug Arnett <dougarnett@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625232}
10 files changed