Remove key preview backing view

This change re-origanizes view hierarchy of IME's input view.

Change-Id: I9d0a07692d0f41de3345d207366393bcd5424f7e
diff --git a/java/res/layout/input_view.xml b/java/res/layout/input_view.xml
index 1ffb8a3..78217b0 100644
--- a/java/res/layout/input_view.xml
+++ b/java/res/layout/input_view.xml
@@ -23,13 +23,8 @@
     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
@@ -37,17 +32,14 @@
         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_alignParentBottom="true"
-        android:layout_width="match_parent"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content" />
 </com.android.inputmethod.latin.InputView>