Reland of [Android][Telemetry] Add support for multiple power monitors

tools/telemetry/telemetry/internal/platform/power_monitor/power_monitor_controller_unittest.py

Index: tools/telemetry/telemetry/internal/platform/power_monitor/power_monitor_controller_unittest.py
diff --git a/tools/telemetry/telemetry/internal/platform/power_monitor/power_monitor_controller_unittest.py b/tools/telemetry/telemetry/internal/platform/power_monitor/power_monitor_controller_unittest.py
index e4368107f4bbfd08bc159195caeb30ed2834bc7f..17140d19964b83d0d3f6ae091f6f7bec642afe33 100644
--- a/tools/telemetry/telemetry/internal/platform/power_monitor/power_monitor_controller_unittest.py
+++ b/tools/telemetry/telemetry/internal/platform/power_monitor/power_monitor_controller_unittest.py
@@ -25,7 +25,17 @@
 
     class P2(power_monitor.PowerMonitor):
       def __init__(self, value):
-        self._value = value
+        self._value = {'P2': value}
+      def CanMonitorPower(self):
+        return True
+      def StartMonitoringPower(self, browser):
+        pass
+      def StopMonitoringPower(self):
+        return self._value
+
+    class P3(power_monitor.PowerMonitor):
+      def __init__(self, value):
+        self._value = {'P3': value}
       def CanMonitorPower(self):
         return True
       def StartMonitoringPower(self, browser):
@@ -35,10 +45,12 @@
 
     battery = battery_utils.BatteryUtils(None)
     controller = power_monitor_controller.PowerMonitorController(
-        [P1(), P2(1), P2(2)], battery)
+        [P1(), P2(1), P3(2)], battery)
     self.assertEqual(controller.CanMonitorPower(), True)
     controller.StartMonitoringPower(None)
-    self.assertEqual(controller.StopMonitoringPower(), 1)
+    controller_returns = controller.StopMonitoringPower()
+    self.assertEqual(controller_returns['P2'], 1)
+    self.assertEqual(controller_returns['P3'], 2)
 
   @mock.patch.object(battery_utils, 'BatteryUtils')
   def testReenableCharingIfNeeded(self, mock_battery):