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 4d36619ab5c661fca1ebe7526473152b376d5933..c63d4aab3cee28e48cdd585dcf0c62fd98321e96 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -51610,15 +51610,22 @@ Therefore, the affected-histogram name has to have at least one dot in it.
     Types X, commits Y as the top suggestion.
   </int>
   <int value="2" label="X -&gt; X(1)">
-    Types X, commits X as the non-top suggestion.
+    Types X, commits X as the 2nd suggestion.
   </int>
   <int value="3" label="X -&gt; Y(1)">
-    Types X, commits Y as the non-top suggestion.
+    Types X, commits Y as the 2nd suggestion.
   </int>
-  <int value="4" label="Prediction">Commits a prediction suggestion.</int>
-  <int value="5" label="Revert">
+  <int value="4" label="X -&gt; X(2)">
+    Types X, commits X as the 3rd/other suggestion.
+  </int>
+  <int value="5" label="X -&gt; Y(2)">
+    Types X, commits Y as the 3rd/other suggestion.
+  </int>

[Ilya Sherman, 2015/03/23 21:00:56]

Please either add new items at the end of the enum, or rename the histogram. 
The histograms dashboard is not smart enough to know how to associate different
labels for different backing enum constants depending on the app version number,
so you'll need to keep the labels consistent in order for old data to be
viewable.  If you don't care about old data being viewable, then please rename
the histogram and mark the old one as <obsolete>, so anyone else who encounters
the histogram isn't tripped up by the change in labels.

[Shu Chen, 2015/03/24 03:24:45]

Done. I've made a new histogram InputMethod.Commit.Type2 referring to
IMECommitType2.
As for InputMethod.PkCommit.Type, it is a un-launched feature, so we don't care
about the history data, so I didn't make a new one but just link it to
IMECommitType2.

Is that OK?

[Ilya Sherman, 2015/03/24 03:51:06]

Yep, if the histogram is for an unlaunched feature, there shouldn't be much data
for it, and so it should be fine to just change the backing histogram.

By the way, please also take a moment to update the backing JS code to warn
future editors of the code to only append items to the enum, so that this
doesn't come up again as an issue in the future :)

+  <int value="6" label="Prediction">Commits a prediction suggestion.</int>
+  <int value="7" label="Revert">
     Reverts the previous auto-corrected and committed word.
   </int>
+  <int value="8" label="Voice">The commit is triggered by voice input.</int>
 </enum>
 
 <enum name="IMECorrectionLevel" type="int">