Revert "Remove key preview backing view"

This reverts commit 2dfcfc5013eee2fbd19a5830ff70943bd6c1bee2.

Change-Id: I96c691b2e9c92be456420196cd7361d03ea4f3e9
bug: 10541453
diff --git a/java/res/layout/input_view.xml b/java/res/layout/input_view.xml
index 78217b0..1ffb8a3 100644
--- a/java/res/layout/input_view.xml
+++ b/java/res/layout/input_view.xml
@@ -23,8 +23,13 @@
     android:orientation="vertical"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:gravity="bottom|center_horizontal"
 >
+    <!-- The height of key_preview_backing view will automatically be determined by code. -->
+    <View
+        android:id="@+id/key_preview_backing"
+        android:layout_width="match_parent"
+        android:layout_height="0dp" />
+
     <!-- To ensure that key preview popup is correctly placed when the current system locale is
          one of RTL locales, layoutDirection="ltr" is needed in the SDK version 17+. -->
     <com.android.inputmethod.latin.suggestions.SuggestionStripView
@@ -32,14 +37,17 @@
         android:layoutDirection="ltr"
         android:layout_width="match_parent"
         android:layout_height="@dimen/suggestions_strip_height"
+        android:gravity="center_vertical"
         android:paddingRight="@dimen/suggestions_strip_padding"
         android:paddingLeft="@dimen/suggestions_strip_padding"
         style="?attr/suggestionStripViewStyle" />
+
     <!-- To ensure that key preview popup is correctly placed when the current system locale is
          one of RTL locales, layoutDirection="ltr" is needed in the SDK version 17+. -->
     <com.android.inputmethod.keyboard.MainKeyboardView
         android:id="@+id/keyboard_view"
         android:layoutDirection="ltr"
-        android:layout_width="wrap_content"
+        android:layout_alignParentBottom="true"
+        android:layout_width="match_parent"
         android:layout_height="wrap_content" />
 </com.android.inputmethod.latin.InputView>