Update health@1.0 batteryVoltage units.

Both framework BatteryService and all implementations (that uses
BatteryMonitor) uses millivolts for batteryVoltage.

maxChargingVoltage is microvolts and that is correct.

Fixes: 115881119
Test: treehugger

Change-Id: I64044489fe6d56e0d211085d9536fe5cfd95efc4
diff --git a/current.txt b/current.txt
index 69996dd..cdd6f68 100644
--- a/current.txt
+++ b/current.txt
@@ -396,6 +396,7 @@
 d702fb01dc2a0733aa820b7eb65435ee3334f75632ef880bafd2fb8803a20a58 android.hardware.gnss@1.0::IGnssMeasurementCallback
 7c7721c0f773fcf422b71a4f558545e9e36acc973e58ca51e5bd53905cf46bc0 android.hardware.graphics.bufferqueue@1.0::IGraphicBufferProducer
 d4fea995378bb4f421b4e24ccf68cad2734ab07fe4f874a126ba558b99df5766 android.hardware.graphics.composer@2.1::IComposerClient
+65a021fa89085b62fc96b2b6d3bef2f9103cf4d63379c68bc154fd9eef672852 android.hardware.health@1.0::types
 b7ecf29927055ec422ec44bf776223f07d79ad9f92ccf9becf167e62c2607e7a android.hardware.keymaster@4.0::IKeymasterDevice
 574e8f1499436fb4075894dcae0b36682427956ecb114f17f1fe22d116a83c6b android.hardware.neuralnetworks@1.0::IPreparedModel
 417ab60fe1ef786778047e4486f3d868ebce570d91addd8fe4251515213072de android.hardware.neuralnetworks@1.0::types
diff --git a/health/1.0/types.hal b/health/1.0/types.hal
index 377d1bd..90b8bb1 100644
--- a/health/1.0/types.hal
+++ b/health/1.0/types.hal
@@ -190,7 +190,13 @@
     /** Remaining battery capacity in percent */
     int32_t batteryLevel;
 
-    /** Instantaneous battery voltage in uV */
+    /**
+     * Instantaneous battery voltage in millivolts (mV).
+     *
+     * Historically, the unit of this field is microvolts (uV), but all
+     * clients and implementations uses millivolts in practice, making it
+     * the de-facto standard.
+     */
     int32_t batteryVoltage;
 
     /** Instantaneous battery temperature in tenths of degree celcius */