Unnecessary view on top of CoordinatorLayout

Question

View Hierarchy

<LinearLayout>
<Toolbar>..
</Toolbar>
<FrameLayout>
<CoordinatorLayout>..
<FrameLayout>
</FrameLayout>
</CoordinatorLayout>
</FrameLayout>
</LinearLayout>

Want to get rid of that dark blue strip . Not sure why Co-ordinatorLayout is appending this view on the top. I tried replacing it with LinearLayout which led to desired results. Not able to figure out why and what view is being displayed as the blue dark strip.

toolbar_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_marginTop="20dp"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@color/white"
        app:title="DISCOVER"
        app:titleTextAppearance="@style/TextAppearance.MyApp.Widget.ActionBar.Title" />

    <View
        style="@style/Divider"
        android:background="@color/grey_light" />

    <FrameLayout
        android:id="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/white">

    </FrameLayout>

</LinearLayout>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.discover.MainActivity">

    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.discover.MainActivity"
    tools:showIn="@layout/activity_main"
    android:layout_margin="0dp"
    android:background="#11a2cb"></FrameLayout>

</android.support.design.widget.CoordinatorLayout>

BaseActivity.java

@Override
    public void setContentView(int layoutResID) {
        super.setContentView(R.layout.toolbar_layout);
        mToolbar = (Toolbar) findViewById(R.id.toolbar);
        mContentlayout = (FrameLayout) findViewById(R.id.content);
        setSupportActionBar(mToolbar);
        getLayoutInflater().inflate(layoutResID, mContentlayout);
    }

In MainActivity I am using setContentView(R.layout.activity_main)

Answer 1

Solution:

Adding android:fitsSystemWindows="true" to the root layout ie LinearLayout in my case worked like a charm.

Cause:

I am still wondering what mysterious view was being displayed. If anybody could point out, please do respond for understanding the issue more clearly.