Remove SubresourceFilter.SafeBrowsing.CheckDispatchTime metric

This metric was helpful in narrowing down problems to SafetyNet, but
there are better SafeBrowsing internal metrics for this now.

Bug: None
Change-Id: I38e07af1b4923a98333a45d9b61b1a00c5ce5ae4
Reviewed-on: https://chromium-review.googlesource.com/1060260Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558864}

components/subresource_filter/content/browser/subresource_filter_safe_browsing_client_request.cc

@@ -13,7 +13,6 @@
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "components/subresource_filter/content/browser/subresource_filter_safe_browsing_client.h"
-#include "components/subresource_filter/core/common/time_measurements.h"
 #include "content/public/browser/browser_thread.h"
 #include "url/gurl.h"
 
@@ -49,8 +48,6 @@ void SubresourceFilterSafeBrowsingClientRequest::Start(const GURL& url) {
   start_time_ = base::TimeTicks::Now();
   bool synchronous_finish =
       database_manager_->CheckUrlForSubresourceFilter(url, this);
-  UMA_HISTOGRAM_MICRO_TIMES("SubresourceFilter.SafeBrowsing.CheckDispatchTime",
-                            (base::TimeTicks::Now() - start_time_));
   if (synchronous_finish) {
     request_completed_ = true;
     SendCheckResultToClient(false /* served_from_network */,

tools/metrics/histograms/histograms.xml

@@ -92516,6 +92516,10 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="SubresourceFilter.SafeBrowsing.CheckDispatchTime"
     units="microseconds">
+  <obsolete>
+    Deprecated in May 2018 in favor of the more general
+    SB2.RemoteCall.CheckDispatchTime.
+  </obsolete>
   <owner>csharrison@chromium.org</owner>
   <summary>
     The microseconds it took to dispatch the Safe Browsing check. This includes