Remove the GoogleUpdate.InstallerExitCode histogram.

It doesn't provide any additional signal over other data sources.

BUG=1138415
R=chromium-metrics-reviews@google.com

Change-Id: I56185e4be8055ff49c72cb3f8016dc943cdbc397
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2479562
Auto-Submit: Greg Thompson <grt@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Reviewed-by: Yann Dago <ydago@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#818186}

chrome/browser/google/google_update_win.cc

@@ -457,10 +457,6 @@ UpdateCheckDriver::~UpdateCheckDriver() {
       base::UmaHistogramSparse("GoogleUpdate.ErrorHresult",
                                update_state_.hresult);
     }
-    if (update_state_.installer_exit_code) {
-      base::UmaHistogramSparse("GoogleUpdate.InstallerExitCode",
-                               *update_state_.installer_exit_code);
-    }
   }
 
   // Clear the driver before calling the delegates because they might call

tools/metrics/histograms/enums.xml

@@ -38146,6 +38146,9 @@ Called by update_gpu_driver_bug_workaround_entries.py.-->
 </enum>
 
 <enum name="InstallStatus">
+  <obsolete>
+    Removed in M88.
+  </obsolete>
   <int value="0" label="FIRST_INSTALL_SUCCESS"/>
   <int value="1" label="INSTALL_REPAIRED"/>
   <int value="2" label="NEW_VERSION_UPDATED"/>

tools/metrics/histograms/histograms_xml/google/histograms.xml

@@ -119,6 +119,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="GoogleUpdate.InstallerExitCode" enum="InstallStatus"
     expires_after="M86">
+  <obsolete>
+    Removed in M88.
+  </obsolete>
   <owner>grt@chromium.org</owner>
   <owner>ydago@chromium.org</owner>
   <summary>