Adding UMA stat when generated password set for newly created PasswordFormManager.

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 e21ad20542c5da3cd945e9d873ff6730a6246adc..fd0095e8e1ac60475d7e0c3a202c728ae5c1eed9 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -27708,6 +27708,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="PasswordManager.GeneratedFormHasNoFormManager" enum="Boolean">

[Ilya Sherman, 2015/06/28 02:19:11]

Please define and use a custom boolean here, with labels like "Has form manager"
and "Lacks for manager".

[Deepak, 2015/06/29 04:01:49]

Done.

+  <owner>gcasto@chromium.org</owner>
+  <owner>vabr@chromium.org</owner>
+  <owner>deepak.m1@samsung.com</owner>
+  <summary>
+    Indicates if the generation state of a password was changed but existing
+    form was not found.

[Ilya Sherman, 2015/06/28 02:19:11]

nit: Suggested rephrasing (feel free to refine further): "When the generation
state of a password was changed, records whether an existing form corresponding
to the password was found."

[Deepak, 2015/06/29 04:01:49]

Done.

+  </summary>
+</histogram>
+
 <histogram name="PasswordManager.InfoBarResponse" enum="InfoBarResponse">
   <owner>dubroy@chromium.org</owner>
   <owner>vabr@chromium.org</owner>