Add lcd_density to StartArcMiniContainerRequest

This will be used to inject the density from chrome
to Android.

BUG=b:66995734
TEST=manual

Change-Id: I4cc7e1387389e1cb5c7e099584c12763ed1c5988
Reviewed-on: https://chromium-review.googlesource.com/1197393
Commit-Ready: Mitsuru Oshima <oshima@chromium.org>
Tested-by: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
diff --git a/dbus/login_manager/arc.proto b/dbus/login_manager/arc.proto
index e1ab900..16dc3fa 100644
--- a/dbus/login_manager/arc.proto
+++ b/dbus/login_manager/arc.proto
@@ -12,6 +12,8 @@
 // in the SessionManagerInterface.StartArcMiniContainer method.
 message StartArcMiniContainerRequest {
   optional bool native_bridge_experiment = 1 [default = false];
+  // The density value passed to "ro.sf.lcd_density" property.
+  optional int32 lcd_density = 2 [default = -1];
 }
 
 // ARC upgrade options sent from Chrome to session manager. This message is used