Add UMA and Rappor metrics to capture URLs passed in at startup.

tools/metrics/rappor/rappor.xml

 <!--
 Copyright 2015 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <rappor-configuration>
 <!--
 This file is used to generate a comprehensive list of Chrome rappor metrics
 along with a detailed description for each histogram. See the design doc at
@@ skipping 13 matching lines @@
     Stricter parameters for metrics collected from a broader population.
   </summary>
   <parameters num-cohorts="128" bytes="1" hash-functions="2" fake-prob="0.5"
       fake-one-prob="0.5" one-coin-prob="0.75" zero-coin-prob="0.25"
       reporting-level="COARSE"/>
 </rappor-parameters>
 
 <rappor-parameters name="ETLD_PLUS_ONE">
   <summary>
     Deprecated parameters for collecting the domain and registry of a URL from
-    UMA opt-in users.
+    UMA opt-in users. Should use UMA_RAPPOR_TYPE instead.
   </summary>
   <parameters num-cohorts="128" bytes="16" hash-functions="2" fake-prob="0.5"
       fake-one-prob="0.5" one-coin-prob="0.75" zero-coin-prob="0.25"
       reporting-level="FINE"/>
 </rappor-parameters>
 
 <rappor-parameters name="SAFEBROWSING_RAPPOR_TYPE">
   <summary>
     Parameters for metrics related to Safe Browsing, collected from all user
     with safe browsing enabled.
@@ skipping 493 matching lines @@
   </summary>
 </rappor-metric>
 
 <rappor-metric name="SoftwareReporter.FoundUwS" type="COARSE_RAPPOR_TYPE">
   <owner>mad@chromium.org</owner>
   <summary>
     The IDs of unwanted software found by the software reporter tool.
   </summary>
 </rappor-metric>
 
+<rappor-metric name="Startup.BrowserLaunchURL" type="UMA_RAPPOR_TYPE">
+  <owner>rkaplow@chromium.org</owner>
+  <summary>
+    The eTLD+1 of a URL that was passed in to be launched at Chrome startup.
+  </summary>
+</rappor-metric>
+
 <rappor-metric name="WebComponents.DocumentRegisterElement"
     type="ETLD_PLUS_ONE">
   <owner>kojii@chromium.org</owner>
   <summary>
     The host of a URL that used Document::RegisterElement().
   </summary>
 </rappor-metric>
 
 <rappor-metric name="WebComponents.ElementCreateShadowRoot"
     type="ETLD_PLUS_ONE">
@@ skipping 104 matching lines @@
     <flag>Bit 1: IS_REPEAT_VISIT</flag>
     <summary>
       Bitfield of the state from an SSL warning interstitial.
     </summary>
   </flags-field>
 </rappor-metric>
 
 </rappor-metrics>
 
 </rappor-configuration>