Input method root view should have BOTTOM gravity.

The window had BOTTOM gravity, but the root view was using the
LinearLayout default (START | TOP), meaning an IME with a tall
inputArea could effectively push the navigation bar guard view
off screen.

This change simply uses BOTTOM instead of TOP for the root view.

Bug:11237795
Change-Id: I681c2b1eddac53589e0d168f09a183d67b1e5322
diff --git a/core/res/res/layout/input_method.xml b/core/res/res/layout/input_method.xml
index 00a3990..e50da00 100644
--- a/core/res/res/layout/input_method.xml
+++ b/core/res/res/layout/input_method.xml
@@ -23,6 +23,7 @@
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:orientation="vertical"
+    android:gravity="start|bottom"
     >
 
     <LinearLayout