title: LinearLayout not wrapping content
body: <p>I used LinearLayout to stack 4 images horizontally and it works well except for the height. It seems that the linearlayout is not properly wrapping its content. If I don't set the images' scale type to fitStart, they will be centered inside the linearlayout.</p>
  
  <p>Here is my layout below:</p>
  
  <p><img src="https://i.stack.imgur.com/hchQq.png" alt="linearlayout">  </p>
  
  <pre><code>&lt;LinearLayout
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_gravity="top"
      android:orientation="horizontal"
      android:weightSum="4"
      android:layout_marginLeft="40dp"
      android:layout_marginRight="40dp"&gt;
  
      &lt;ImageView
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:id="@+id/imageView"
          android:src="@drawable/header1"
          android:layout_weight="1"
          android:scaleType="fitStart" /&gt;
  
      &lt;ImageView
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:id="@+id/imageView2"
          android:layout_gravity="center_vertical"
          android:src="@drawable/header2"
          android:layout_weight="1"
          android:scaleType="fitStart" /&gt;
  
      &lt;ImageView
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:id="@+id/imageView3"
          android:layout_gravity="center_vertical"
          android:src="@drawable/header3color"
          android:layout_weight="1"
          android:scaleType="fitStart" /&gt;
  
      &lt;ImageView
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:id="@+id/imageView4"
          android:src="@drawable/header4"
          android:layout_weight="1"
          android:scaleType="fitStart" /&gt;
  &lt;/LinearLayout&gt;
  </code></pre>