Add csharrison to some histograms_xml OWNERS

Was previously an OWNER of all histograms.xml before the split. Now
moving to sub-owners of directories I tend to do reviews for.

Bug: None
Change-Id: I34de0dd4f0a17c014e5f1bcdc96046b78483253b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2444029
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827142}

tools/metrics/histograms/histograms_xml/net/OWNERS

@@ -5,3 +5,12 @@ dschinazi@chromium.org
 # If none of these reviewers are available, please send CLs to
 # <chromium-metrics-reviews@google.com>. See tools/metrics/histograms/OWNERS
 # for details.
+
+
+# Prefer chromium-metrics-reviews@google.com or the above owners instead.
+# Use the following owners only if:
+#  - The reviewer is available for review.
+#  - You work in the same area as them.
+#  - They are already a good reviewer for the non-metrics part of the CL.
+# See tools/metrics/histograms/histograms_xml/OWNERS for details.
+csharrison@chromium.org

tools/metrics/histograms/histograms_xml/others/OWNERS

@@ -4,5 +4,6 @@
 #  - You work in the same area as them.
 #  - They are already a good reviewer for the non-metrics part of the CL.
 # See tools/metrics/histograms/histograms_xml/OWNERS for details.
+csharrison@chromium.org
 tbansal@chromium.org
 tby@chromium.org

tools/metrics/histograms/histograms_xml/page/OWNERS

+# Prefer chromium-metrics-reviews@google.com instead.
+# Use the following owners only if:
+#  - The reviewer is available for review.
+#  - You work in the same area as them.
+#  - They are already a good reviewer for the non-metrics part of the CL.
+# See tools/metrics/histograms/OWNERS for details.
+csharrison@chromium.org

tools/metrics/histograms/histograms_xml/subresource/OWNERS

@@ -4,4 +4,5 @@
 #  - You work in the same area as them.
 #  - They are already a good reviewer for the non-metrics part of the CL.
 # See tools/metrics/histograms/OWNERS for details.
+csharrison@chromium.org
 tbansal@chromium.org