Fix DisplayMetrics KeyboardListener dependency

Summary:
public
KeyboardListener needs DisplayMetrics to be initialized when it is attached. At
the moment, this breaks easily whenever we change these components, since DisplayMetrics are intialized
in a module and KeyboardListener is created eagerly in ReactRootView, whereas
ReactRootView can exist without the instance.
This changes to create DisplayMetrics as soon as possible, when the react
instance is built. The KeyboardListener is created and attached after the ReactRootView is
attached to an existing instance, point at which DisplayMetrics have to be
initialized.

Reviewed By: dmmiller

Differential Revision: D2911351

fb-gh-sync-id: 64d1805c5d5b2f6876adb694b565a2df059b381d

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModuleConstants.java

@@ -12,7 +12,6 @@ package com.facebook.react.uimanager;
 import java.util.HashMap;
 import java.util.Map;
 
-import android.text.InputType;
 import android.util.DisplayMetrics;
 import android.view.accessibility.AccessibilityEvent;
 import android.widget.ImageView;
@@ -80,7 +79,7 @@ import com.facebook.react.uimanager.events.TouchEventType;
         .build();
   }
 
-  public static Map<String, Object> getConstants(DisplayMetrics displayMetrics) {
+  public static Map<String, Object> getConstants() {
     HashMap<String, Object> constants = new HashMap<String, Object>();
     constants.put(
         "UIView",
@@ -92,6 +91,7 @@ import com.facebook.react.uimanager.events.TouchEventType;
                 "ScaleAspectFill",
                 ImageView.ScaleType.CENTER_CROP.ordinal())));
 
+    DisplayMetrics displayMetrics = DisplayMetricsHolder.getDisplayMetrics();
     constants.put(
         "Dimensions",
         MapBuilder.of(