Use TimeDelta::operator/() more, extensions/ edition.

Bug: 1104532
Change-Id: I07fcafbe11cf4a00af1549f4a4ae3ef17db1ce0f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354467
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Reviewed-by: David Bertoni <dbertoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798000}

extensions/browser/api/web_request/web_request_time_tracker.cc

@@ -65,8 +65,7 @@ void ExtensionWebRequestTimeTracker::AnalyzeLogRequest(
   // extra delay the extension adds is likely to be noise.
   constexpr auto kMinRequestTimeToCare = base::TimeDelta::FromMilliseconds(10);
   if (request_duration >= kMinRequestTimeToCare) {
-    double percentage = log.block_duration.InMillisecondsF() /
-                        request_duration.InMillisecondsF();
+    double percentage = log.block_duration / request_duration;
     UMA_HISTOGRAM_PERCENTAGE("Extensions.NetworkDelayPercentage",
                              static_cast<int>(100 * percentage));
   }

extensions/renderer/extension_throttle_simulation_unittest.cc

@@ -638,10 +638,10 @@ TEST(URLRequestThrottlerSimulation, PerceivedDowntimeRatio) {
     Stats stats;
 
     void PrintTrialDescription() {
-      double duration_minutes =
-          static_cast<double>(duration.InSeconds()) / 60.0;
-      double interval_minutes =
-          static_cast<double>(average_client_interval.InSeconds()) / 60.0;
+      const double duration_minutes =
+          duration / base::TimeDelta::FromMinutes(1);
+      const double interval_minutes =
+          average_client_interval / base::TimeDelta::FromMinutes(1);
       VerboseOut("Trial with %.2f min downtime, avg. interval %.2f min.\n",
                  duration_minutes, interval_minutes);
     }