Support adding ReactView in CollapsingTopBar

android/app/src/main/java/com/reactnativenavigation/params/parsers/CollapsingTopBarParamsParser.java

     }
 
     private CollapseBehaviour getCollapseBehaviour() {
-        if (hasBackgroundImage()) {
+        if (hasBackgroundImage() || hasReactView()) {
             return new CollapseTopBarBehaviour();
         }
         if (titleBarHideOnScroll && drawBelowTopBar) {

android/app/src/main/java/com/reactnativenavigation/views/collapsingToolbar/CollapsingTopBar.java

 package com.reactnativenavigation.views.collapsingToolbar;
 
 import android.content.Context;
+import android.content.res.TypedArray;
+import android.os.Bundle;
 import android.view.View;
 import android.widget.ScrollView;
 
 import com.reactnativenavigation.params.CollapsingTopBarParams;
+import com.reactnativenavigation.params.NavigationParams;
 import com.reactnativenavigation.utils.ViewUtils;
 import com.reactnativenavigation.views.TitleBar;
 import com.reactnativenavigation.views.TopBar;
 
 public class CollapsingTopBar extends TopBar implements CollapsingView {
     private CollapsingTopBarBackground collapsingTopBarBackground;
+    private CollapsingTopBarReactView headerView;
     private ScrollListener scrollListener;
     private float finalCollapsedTranslation;
     private CollapsingTopBarParams params;
     private final ViewCollapser viewCollapser;
+    private final int topBarHeight;
 
     public CollapsingTopBar(Context context, final CollapsingTopBarParams params) {
         super(context);
         this.params = params;
-        createCollapsingTopBar(params);
+        topBarHeight = calculateTopBarHeight();
+        createBackgroundImage(params);
+        createReactView(params);
         calculateFinalCollapsedTranslation(params);
         viewCollapser = new ViewCollapser(this);
     }
             @Override
             public void run() {
                 if (params.hasBackgroundImage()) {
-                    finalCollapsedTranslation =
-                            getCollapsingTopBarBackground().getCollapsedTopBarHeight() - getHeight();
+                    finalCollapsedTranslation = getCollapsedHeight() - getHeight();
                 } else {
                     finalCollapsedTranslation = -titleBar.getHeight();
                 }
         this.scrollListener = scrollListener;
     }
 
-    private void createCollapsingTopBar(CollapsingTopBarParams params) {
+    private void createBackgroundImage(CollapsingTopBarParams params) {
         if (params.hasBackgroundImage()) {
             collapsingTopBarBackground = new CollapsingTopBarBackground(getContext(), params);
             LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, (int) CollapsingTopBarBackground.MAX_HEIGHT);
         }
     }
 
+    private void createReactView(CollapsingTopBarParams params) {
+        if (params.hasReactView()) {
+            headerView = new CollapsingTopBarReactView(getContext(),
+                    params.reactViewId,
+                    new NavigationParams(Bundle.EMPTY));
+            LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, (int) ViewUtils.convertDpToPixel(400));
+            titleBarAndContextualMenuContainer.addView(headerView, lp);
+        }
+    }
+
     @Override
     protected TitleBar createTitleBar() {
         if (params.hasBackgroundImage()) {
             return new CollapsingTitleBar(getContext(),
-                    collapsingTopBarBackground.getCollapsedTopBarHeight(),
+                    getCollapsedHeight(),
                     scrollListener);
         } else {
             return super.createTitleBar();
         }
     }
 
-    public CollapsingTopBarBackground getCollapsingTopBarBackground() {
-        return collapsingTopBarBackground;
-    }
-
     @Override
     public void collapse(CollapseAmount amount) {
         viewCollapser.collapse(amount);
 
     public int getCollapsedHeight() {
         if (params.hasBackgroundImage()) {
-            return collapsingTopBarBackground.getCollapsedTopBarHeight();
+            return topBarHeight;
+        } else if (params.hasReactView()) {
+            return topBarHeight;
         } else if (topTabs != null) {
             return topTabs.getHeight();
         } else {
         }
     }
 
+    private int calculateTopBarHeight() {
+        int[] attrs = new int[] {android.R.attr.actionBarSize};
+        TypedArray ta = getContext().obtainStyledAttributes(attrs);
+        final int result = ta.getDimensionPixelSize(0, -1);
+        ta.recycle();
+        return result;
+    }
+
     @Override
     public float getCurrentCollapseValue() {
         return getTranslationY();

android/app/src/main/java/com/reactnativenavigation/views/collapsingToolbar/CollapsingTopBarBackground.java

 package com.reactnativenavigation.views.collapsingToolbar;
 
 import android.content.Context;
-import android.content.res.TypedArray;
 import android.widget.FrameLayout;
 import android.widget.ImageView;
 
     private final CollapsingTopBarParams params;
     private SimpleDraweeView backdrop;
     private Scrim scrim;
-    private int topBarHeight = -1;
 
     public CollapsingTopBarBackground(Context context, CollapsingTopBarParams params) {
         super(context);
         addView(scrim);
     }
 
-    public int getCollapsedTopBarHeight() {
-        if (topBarHeight > -1) {
-            return topBarHeight;
-        }
-        calculateTopBarHeight();
-        return topBarHeight;
-    }
-    private void calculateTopBarHeight() {
-        int[] attrs = new int[] {android.R.attr.actionBarSize};
-        TypedArray ta = getContext().obtainStyledAttributes(attrs);
-        topBarHeight = ta.getDimensionPixelSize(0, -1);
-        ta.recycle();
-    }
-
     public void collapse(float collapse) {
         scrim.collapse(collapse);
     }

android/app/src/main/java/com/reactnativenavigation/views/collapsingToolbar/CollapsingTopBarReactView.java

+package com.reactnativenavigation.views.collapsingToolbar;
+
+import android.content.Context;
+
+import com.reactnativenavigation.params.NavigationParams;
+import com.reactnativenavigation.views.ContentView;
+
+public class CollapsingTopBarReactView extends ContentView {
+    public CollapsingTopBarReactView(Context context, String screenId, NavigationParams navigationParams) {
+        super(context, screenId, navigationParams);
+    }
+}