Improve histogram and actions for CBD dialog

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index fd2b1cad344a9d77b5f907f50bf3e65d0ee5b2f6..0581fc14032a7dfca0ccfca10dd9f1a2d9e8e040 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -24111,6 +24111,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="History.ClearBrowsingData.TimeSpentInDialog" units="ms">
+  <owner>dullweber@chromium.org</owner>
+  <owner>msramek@chromium.org</owner>
+  <summary>
+    Time spent in Clear Browsing Data dialog. From opening the dialog until data

[rkaplow, 2017/06/27 21:40:33]

may want to clarify - this only records when data is cleared, but if data is not
cleared it is not recorded?

[dullweber, 2017/06/28 09:09:33]

yes, that is right. I will look into recording aborts as well but only very few
users exit the dialog without a deletion. I improved the summary

+    is cleared.
+  </summary>
+</histogram>
+
 <histogram name="History.ClearBrowsingData.UserDeletedCookieOrCache"
     enum="CookieOrCacheDeletion">
   <owner>msramek@chromium.org</owner>