Add UMA metrics to phishguard pings

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 68206764ad76095705618b2d6a55f02b4f3164a1..3e6f13670da33e2e6f83278580af28edfe1e2995 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -49929,7 +49929,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <owner>jialiul@chromium.org</owner>
   <owner>nparker@chromium.org</owner>
   <summary>
-    Verdict types returned by Safe Browsing server for password reuse events.
+    Deprecated. Replaced by
+    &quot;PasswordProtection.Verdict.ProtectedPasswordEntry&quot;. Verdict types

[Ilya Sherman, 2017/05/12 21:07:44]

Please mark this histogram as <obsolete>.

[Jialiu Lin, 2017/05/12 21:50:55]

Done.

+    returned by Safe Browsing server for password reuse events.
   </summary>
 </histogram>
 
@@ -49958,7 +49960,19 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <owner>jialiul@chromium.org</owner>
   <owner>nparker@chromium.org</owner>
   <summary>
-    Verdict types returned by Safe Browsing server for unfamiliar login pages.
+    Deprecated. Replaced by
+    &quot;PasswordProtection.Verdict.PasswordFieldOnFocus&quot;. Verdict types

[Ilya Sherman, 2017/05/12 21:07:44]

Please mark this histogram as <obsolete>.

[Jialiu Lin, 2017/05/12 21:50:54]

Done.

+    returned by Safe Browsing server for unfamiliar login pages.
+  </summary>
+</histogram>
+
+<histogram name="PasswordProtection.Verdict" enum="PasswordProtectionVerdict">
+  <owner>jialiul@chromium.org</owner>
+  <owner>nparker@chromium.org</owner>
+  <summary>
+    Verdict types returned by Safe Browsing server for a password protection
+    request. Request can be triggered when user focuses on a password field or
+    enters a protected password.
   </summary>
 </histogram>
 
@@ -89834,6 +89848,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <affected-histogram name="PasswordManager.SavePasswordPromptResponse"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="PasswordProtectionTrigger">
+  <suffix name="PasswordFieldOnFocus"/>
+  <suffix name="ProtectedPasswordEntry"/>

[Ilya Sherman, 2017/05/12 21:07:44]

nit: Please add a brief label for each suffix.

[Jialiu Lin, 2017/05/12 21:50:55]

Done.

+  <affected-histogram name="PasswordProtection.RequestOutcome"/>

[Ilya Sherman, 2017/05/12 21:07:44]

Please mark the underlying histogram as <obsolete>, since only the suffixes are
emitted to.  (I'm actually not 100% sure whether marking it as <obsolete> will
also mark the suffixes as obsolete.  If you don't want to test this and
potentially need to land a small fix-up CL, you can instead add the attribute
base="true" to the underlying histogram.)

[Jialiu Lin, 2017/05/12 21:50:55]

base="true" sounds better. Thanks for pointing this out!

+  <affected-histogram name="PasswordProtection.Verdict"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="PasswordReuseSourceRealm" separator=".">
   <suffix name="FromHttpRealm"
       label="The account in question was saved on an HTTP site."/>