Improve readability of power monitoring code and add additional

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

Index: tools/telemetry/telemetry/internal/platform/power_monitor/pm_mock.py
diff --git a/tools/telemetry/telemetry/internal/platform/power_monitor/pm_mock.py b/tools/telemetry/telemetry/internal/platform/power_monitor/pm_mock.py
new file mode 100644
index 0000000000000000000000000000000000000000..d9bbab5ba870105a120d31713953f3c7e690b207
--- /dev/null
+++ b/tools/telemetry/telemetry/internal/platform/power_monitor/pm_mock.py
@@ -0,0 +1,61 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+class MockBrowserBackend(object):
+  def __init__(self, package):
+    self.package = package
+
+class MockBrowser(object):
+  def __init__(self, package):
+    self._browser_backend = MockBrowserBackend(package)
+
+class MockBattery(object):
+  def __init__(self,
+               power_results,
+               starts_charging=True,
+               voltage=4.0,
+               fuelgauge=None):
+    # voltage in millivolts
+    self._power_results = power_results
+    self._charging = starts_charging
+    self._voltage = voltage
+    self._fuelgauge = fuelgauge if fuelgauge else []
+    self._fuel_idx = 0
+
+  def SupportsFuelGauge(self):
+    return len(self._fuelgauge) >= 0
+
+  def GetFuelGaugeChargeCounter(self):
+    try:
+      x = self._fuelgauge[self._fuel_idx]
+      self._fuel_idx += 1
+      return x
+    except IndexError:
+      assert False, "Too many GetFuelGaugeChargeCounter() calls."
+
+  def GetCharging(self):
+    return self._charging
+
+  def SetCharging(self, charging):
+    if charging:
+      assert not self._charging, "Mock battery already charging."
+      self._charging = True
+    else:
+      assert self._charging, "Mock battery already not charging."
+      self._charging = False
+
+  def GetPowerData(self):
+    return self._power_results
+
+  def GetBatteryInfo(self):
+    # the voltage returned by GetBatteryInfo() is in millivolts
+    return {'voltage': int(self._voltage*1000)}
+
+class MockPlatformBackend(object):
+  def __init__(self, command_dict=None):
+    self._cdict = (command_dict if command_dict else {})
+
+  def RunCommand(self, command):
+    assert command in self._cdict, "Mock platform error: Unexpected command."
+    return self._cdict[command]