[password autofill] Add stats on provisional save failures.

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 f0c5161e109af3a2c12fd04d7c62fa465c97b961..85e6b7a1f5d3e8933db7bd02c147eb390a8c548d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -9587,6 +9587,14 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="PasswordManager.ProvisionalSaveFailure"
+    enum="ProvisionalSaveFailure">
+  <summary>
+    Breakdown of cases where a password is submitted, but we don't even try and
+    save it. Recorded for every password form submit.
+  </summary>
+</histogram>
+
 <histogram name="PasswordManager.TimesGeneratedPasswordUsed">
   <summary>
     The number of times each generated password has been used to log in.
@@ -20864,6 +20872,16 @@ other types of suffix sets.
   <int value="5" label="SPDY 3.0"/>
 </enum>
 
+<enum name="ProvisionalSaveFailure" type="int">
+  <int value="0" label="SAVING_DISABLED"/>
+  <int value="1" label="EMPTY_PASSWORD"/>
+  <int value="2" label="NO_MATCHING_FORM"/>
+  <int value="3" label="MATCHING_NOT_COMPLETE"/>
+  <int value="4" label="FORM_BLACKLISTED"/>
+  <int value="5" label="INVALID_FORM"/>
+  <int value="6" label="AUTOCOMPLETE_OFF"/>
+</enum>
+
 <enum name="ProxyStatus" type="int">
   <int value="0" label="PROXY_STATUS_IGNORED"/>
   <int value="1" label="PROXY_UNINITIALIZED"/>