getSupportActionBar().setCustomView(view) does not fill entire actionbar

This is all you need to add in your onCreate()

getSupportActionBar().setCustomView(new CustomView(this));
getSupportActionBar().setDisplayShowCustomEnabled(true);

Set your main container to this:

   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="match_parent"
        android:layout_gravity="fill_horizontal"
        android:background="@color/actionbar_color"
        >

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="25dp"
            android:layout_centerInParent="true"
            android:scaleType="fitCenter"
            android:src="@drawable/logo"/>

    </RelativeLayout>

The important part is the android:layout_gravity="fill_horizontal that should solve your problem.

EDIT:

if that did not work try doing this:

View view = getLayoutInflater().inflate(R.layout.actionbar_customized_home, null);
LayoutParams layout = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
getSupportActionBar().setCustomView(view, layout);