[Search] Apply background to entire SearchInput view instead of just EditText

Bug: 199555357
Test: visual
Change-Id: Ice966416e901e7c601b44529d0422798e943e222

src/com/android/launcher3/allapps/SearchUiManager.java

@@ -48,6 +48,19 @@ public interface SearchUiManager {
     @Nullable
     ExtendedEditText getEditText();
 
+    /**
+     * Sets whether EditText background should be visible
+     * @param maxAlpha defines the maximum alpha the background should animates to
+     */
+    default void setBackgroundVisibility(boolean visible, float maxAlpha) {}
+
+    /**
+     * Returns whether a visible background is set on EditText
+     */
+    default boolean getBackgroundVisibility() {
+        return false;
+    }
+
     /**
      * sets highlight result's title
      */