chrome: Fix average 30-sec battery drain UMA metrics.

Copy/paste bug snuck in, which meant we were reporting into the same
histogram twice rather than into two different ones. Correcting.

Change-Id: Ia43697b69ff5603cc931e2dbda62fdb5892305b7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2352189
Auto-Submit: Eric Seckler <eseckler@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Commit-Queue: Tommy Nyquist <nyquist@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797441}

chrome/browser/android/battery/android_battery_metrics.cc

@@ -48,7 +48,8 @@ void ReportAveragedDrain(int capacity_consumed,
         AddCount(capacity_consumed / num_sampling_periods,
                  num_sampling_periods),
         base::Histogram::FactoryGet(
-            kName, /*min_value=*/1, /*max_value=*/100000, /*bucket_count=*/50,
+            kExclusiveName, /*min_value=*/1, /*max_value=*/100000,
+            /*bucket_count=*/50,
             base::HistogramBase::kUmaTargetedHistogramFlag));
   }