cros: Add UMA metrics in migration UI to get more information from migration failures.

tools/metrics/histograms/enums.xml

Index: tools/metrics/histograms/enums.xml
diff --git a/tools/metrics/histograms/enums.xml b/tools/metrics/histograms/enums.xml
index b107d9bdfc682e9dd84baf792ede62f2d56136d0..890d88e4768489686ef6ed4575edbaea12871f2c 100644
--- a/tools/metrics/histograms/enums.xml
+++ b/tools/metrics/histograms/enums.xml
@@ -23695,8 +23695,9 @@ from previous Chrome versions.
   <int value="2" label="Neutral with a verbose warning on sensitive fields"/>
   <int value="3" label="Neutral with a verbose warning after editing a form"/>
   <int value="4" label="Neutral with a verbose warning in Incognito mode"/>
-  <int value="5" label="Neutral with a verbose warning after editing a form or
-      in Incognito mode"/>
+  <int value="5"
+      label="Neutral with a verbose warning after editing a form or in
+             Incognito mode"/>

[Ilya Sherman, 2017/05/31 23:34:45]

Hmm, I'm guessing this is a presubmit formatting correction?  I'm wondering
how/why the code originally landed with the wrong formatting... are we not
running the presubmit at the right time?  (Not something you need to address in
this CL, but if you happen to have a spare moment to investigate, I'd appreciate
it!)

[fukino, 2017/06/01 09:28:38]

Yes, I was asked to run "git cl format ." on git cl upload, and got this change.
I'm still not sure how the original code lands.

The line in question lands in https://codereview.chromium.org/2907153006.
In the presubmit log, I can see
  ** Presubmit Warnings **
  The src directory requires source formatting. Please run git cl format .
But the presubmit passed. (Maybe it's just warning and WAI?)

https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Ftryserver.chromium.linux...

[Ilya Sherman, 2017/06/02 00:04:33]

Thanks for investigating that!  I think this should probably be surfaced as an
error rather than a warning, so as to block the CQ on errors.  I filed a bug:
https://bugs.chromium.org/p/chromium/issues/detail?id=728872

 </enum>
 
 <enum name="MarkNonSecureAsStatus" type="int">
@@ -24293,6 +24294,20 @@ from previous Chrome versions.
   <int value="2" label="LowStorage"/>
 </enum>
 
+<enum name="MigrationUIMigrationResult" type="int">
+  <int value="0" label="Success in new migration"/>
+  <int value="1" label="Success in resumed migration"/>
+  <int value="2" label="Failure in new migration"/>
+  <int value="3" label="Failure in resumed migration"/>
+</enum>
+
+<enum name="MigrationUIRemoveCryptohomeResult" type="int">
+  <int value="0" label="Success in new migration"/>
+  <int value="1" label="Success in resumed migration"/>
+  <int value="2" label="Failure in new migration"/>
+  <int value="3" label="Failure in resumed migration"/>
+</enum>
+
 <enum name="MigrationUIUserChoice" type="int">
   <int value="0" label="Update"/>
   <int value="1" label="Skip"/>