Fixing BatteryStatus ANR

Since getting properties from the BatteryManager can occasionally be
very slow, we get these properties in the background, and return the
result to the UI thread. This prevents the UI thread from hanging on
the slow operations.

Bug: 1163401
Change-Id: I918b36bdabfdf0a1b41063316b64bb41539ce6da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2617468
Commit-Queue: Sam Maier <smaier@chromium.org>
Reviewed-by: Tim Volodine <timvolodine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842178}

services/device/battery/android/java/src/org/chromium/device/battery/BatteryStatusManager.java

@@ -15,6 +15,7 @@ import androidx.annotation.VisibleForTesting;
 
 import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
+import org.chromium.base.task.AsyncTask;
 import org.chromium.device.mojom.BatteryStatus;
 
 /**
@@ -140,10 +141,22 @@ class BatteryStatusManager {
         batteryStatus.level = level;
 
         if (mAndroidBatteryManager != null) {
-            updateBatteryStatus(batteryStatus);
+            // Doing an AsyncTask since querying the BatteryManager might be slow. In the past, it
+            // has caused ANRs when executed on the main thread - see crbug.com/1163401.
+            new AsyncTask<BatteryStatus>() {
+                @Override
+                protected BatteryStatus doInBackground() {
+                    updateBatteryStatus(batteryStatus);
+                    return batteryStatus;
+                }
+                @Override
+                protected void onPostExecute(BatteryStatus batteryStatus) {
+                    mCallback.onBatteryStatusChanged(batteryStatus);
+                }
+            }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
+        } else {
+            mCallback.onBatteryStatusChanged(batteryStatus);
         }
-
-        mCallback.onBatteryStatusChanged(batteryStatus);
     }
 
     private void updateBatteryStatus(BatteryStatus batteryStatus) {