Implement the spring charger replacement UI.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 082857592dcfd6a2e204d8b5dbb3b6fcaeadc460..952d93bb6e2b897999de4643f0078b041a02a764 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -13907,6 +13907,14 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Power.ChargerType" enum="PowerChargerType">
+  <summary>
+    External power supply type such as MAINS_CHARGER, USB_CHARGER,
+    UNCONFIRMED_SPRING_CHARGER, SAFE_SPRING_CHARGER. A sample is reported each
+    time a charger is connected to the device.
+  </summary>
+</histogram>
+
 <histogram name="Power.FirmwareResumeTimeOnAC" units="milliseconds">
   <summary>
     The time that the firmware took to resume the Chrome OS device from
@@ -28201,6 +28209,14 @@ other types of suffix sets.
   <int value="2" label="Brightness Absolute"/>
 </enum>
 
+<enum name="PowerChargerType" type="int">
+  <int value="0" label="Unknown charger"/>
+  <int value="1" label="MAINS charger"/>
+  <int value="2" label="USB Charger"/>
+  <int value="3" label="Unconfirmed Spring Charger"/>
+  <int value="4" label="Safe Spring Charger"/>
+</enum>
+
 <enum name="PreconnectedNavigation" type="int">
   <int value="0" label="No recent pre-connect to the page"/>
   <int value="1" label="Page nav. preceded by a pre-connect"/>