Update Startup Page Histograms

1. Extend Expiration for Settings.StartupPageLoadSettings

2. Remove Settings.StartupPageLoadURLs

Bug: 986512
Change-Id: I0a1a6893cb6594756537d6ed73380b69ee86d16e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1772424Reviewed-by: Ramya Nagarajan <ramyan@chromium.org>
Reviewed-by: Dominic Battré <battre@chromium.org>
Reviewed-by: proberge <proberge@chromium.org>
Commit-Queue: proberge <proberge@chromium.org>
Auto-Submit: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691146}

chrome/browser/prefs/pref_metrics_service.cc

@@ -110,8 +110,6 @@ void PrefMetricsService::RecordLaunchPrefs() {
   if (restore_on_startup == SessionStartupPref::kPrefValueURLs) {
     const base::ListValue* url_list =
         prefs_->GetList(prefs::kURLsToRestoreOnStartup);
-    UMA_HISTOGRAM_CUSTOM_COUNTS("Settings.StartupPageLoadURLs",
-                                url_list->GetSize(), 1, 50, 20);
     // Similarly, check startup pages for known search engine TLD+1s.
     std::string url_text;
     for (size_t i = 0; i < url_list->GetSize(); ++i) {

tools/metrics/histograms/histograms.xml

@@ -127546,7 +127546,7 @@ should be kept until we remove incident reporting. -->
 </histogram>
 
 <histogram name="Settings.StartupPageLoadSettings" enum="SessionStartupPref"
-    expires_after="2019-08-30">
+    expires_after="2020-08-30">
   <owner>ramyan@chromium.org</owner>
   <owner>mpearson@chromium.org</owner>
   <summary>The startup page settings when a profile is loaded.</summary>
@@ -127576,6 +127576,9 @@ should be kept until we remove incident reporting. -->
 </histogram>
 
 <histogram name="Settings.StartupPageLoadURLs">
+  <obsolete>
+    Not needed. Removed August 2019.
+  </obsolete>
   <owner>mpearson@chromium.org</owner>
   <summary>
     The number of URLs to be loaded on startup when a profile is loaded, if the