The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ad9a27a4d180efbc526c04545e9eea31f8dcecb7

commit ad9a27a4d180efbc526c04545e9eea31f8dcecb7
Author: donnd <donnd@chromium.org>
Date: Thu May 11 20:35:32 2017

[TTS] Remove the blacklist and first char metrics.

We were recording the first character of the selection to use as
a hint for triggering.  We don't currently have permission to send
this to Ranker so it's being removed for now, and the histogram being
marked obsolete.

We don't yet have permission to send any content signals to Ranker
so removing some promising ones like word-length from the send-to-ranker
list but keeping the underlying data collection for now.

Remove the entire blacklist and obsoleting the associated histogram.

BUG= 720193 

Review-Url: https://codereview.chromium.org/2875553002
Cr-Commit-Position: refs/heads/master@{#471058}

[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/contextualsearch/ContextualSearchPanelMetrics.java
[delete] https://crrev.com/9ac1e972f92e44597cf8c9a0473fa2fc7f50655e/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchBlacklist.java
[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchManager.java
[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchRankerLogger.java
[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchSelectionController.java
[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchSelectionHandler.java
[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchUma.java
[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/chrome/android/java_sources.gni
[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/tools/metrics/histograms/enums.xml
[modify] https://crrev.com/ad9a27a4d180efbc526c04545e9eea31f8dcecb7/tools/metrics/histograms/histograms.xml