Remove BrowserForSystemProfile user metric action.

According to metrics, this action is only firing a couple times a week.

BUG=482176

Change-Id: I9532cd4db87e5c1a801484eef34c522dfcebf0a7
Reviewed-on: https://chromium-review.googlesource.com/1151087Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582742}

chrome/browser/ui/browser.cc

@@ -408,12 +408,8 @@ Browser::Browser(const CreateParams& params)
   CHECK(IncognitoModePrefs::CanOpenBrowser(profile_));
   CHECK(!profile_->IsGuestSession() || profile_->IsOffTheRecord())
       << "Only off the record browser may be opened in guest mode";
-  DCHECK(!profile_->IsSystemProfile())
+  CHECK(!profile_->IsSystemProfile())
       << "The system profile should never have a real browser.";
-  // TODO(mlerman): After this hits stable channel, see if there are counts
-  // for this metric. If not, change the DCHECK above to a CHECK.
-  if (profile_->IsSystemProfile())
-    base::RecordAction(base::UserMetricsAction("BrowserForSystemProfile"));
 
   // TODO(jeremy): Move to initializer list once flag is removed.
   if (IsFastTabUnloadEnabled())

tools/metrics/actions/actions.xml

@@ -3338,6 +3338,10 @@ should be able to be added at any place in this file.
 </action>
 
 <action name="BrowserForSystemProfile">
+  <obsolete>
+    No longer needed as the number of users affected by https://crbug.com/482176
+    is now approximately zero.
+  </obsolete>
   <owner>mlerman@chromium.org</owner>
   <description>
     A browser opened with the System Profile. Tsk, tsk. Any non-zero amount