Heads-up notifications for low battery warnings.

Falls back to dialogs when heads-up are N/A.

Add new ongoing notification if battery saver mode
is active.  Offer to start battery saver on warnings,
if not already started.

True up BatteryMeterView's levels to the latest threshold
levels.  15% for first warning.

Bug:13329308
Change-Id: Id8ad11a1997079ee7165ae003a8fa1c744462ab3
diff --git a/packages/SystemUI/res/drawable/ic_power_low.xml b/packages/SystemUI/res/drawable/ic_power_low.xml
new file mode 100644
index 0000000..5bb7aba
--- /dev/null
+++ b/packages/SystemUI/res/drawable/ic_power_low.xml
@@ -0,0 +1,28 @@
+<!--
+Copyright (C) 2014 The Android Open Source Project
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+         http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+-->
+<vector xmlns:android="http://schemas.android.com/apk/res/android" >
+    <size
+        android:width="24.0dp"
+        android:height="24.0dp"/>
+
+    <viewport
+        android:viewportWidth="48.0"
+        android:viewportHeight="48.0"/>
+
+    <path
+        android:fill="#FFFFFFFF"
+        android:pathData="M30.0,6.0L30.0,2.0L18.0,2.0l0.0,4.0l-8.0,0.0l0.0,40.0l28.0,0.0L38.0,6.0L30.0,6.0zM26.0,37.0l-4.0,0.0l0.0,-4.0l4.0,0.0L26.0,37.0zM26.0,30.0l-4.0,0.0L22.0,15.0l4.0,0.0L26.0,30.0z"/>
+</vector>