title: findFragmentById for SupportMapFragment returns null in Android Studio
body: <p>Recently I migrated a project from Eclipse to Android Studio. Everything is setup and working fine except for my one fragment which uses a SupportMapFragment.  The below findFragmentById (which worked when building in Eclipse) is now returning null :( </p>
  
  <pre><code>public void onActivityCreated(Bundle savedInstanceState) {
      super.onActivityCreated(savedInstanceState);
      SupportMapFragment m = ((SupportMapFragment) getActivity().getSupportFragmentManager().findFragmentById(R.id.safety_map));
  </code></pre>
  
  <p>snippet of xml...</p>
  
  <pre><code>&lt;FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:map="http://schemas.android.com/apk/res-auto"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:orientation="vertical" &gt;
  
       &lt;fragment
           android:id="@+id/safety_map"
           android:layout_width="fill_parent"
           android:layout_height="fill_parent"
           android:layout_marginBottom="40dp"
           map:cameraTargetLat="@string/livesafe_latitude"
           map:cameraTargetLng="@string/livesafe_longitude"
           map:uiZoomControls="false"
           class="com.google.android.gms.maps.SupportMapFragment"/&gt;
  </code></pre>
  
  <p>Here are my dependencies in my build.gradle:</p>
  
  <pre><code> dependencies {
      //google analytics
      compile 'com.google.apis:google-api-services-analytics:v3-rev103-1.19.0'
      //support library for api 10
      compile 'com.android.support:support-v4:21.0.0'
      //google play services
      compile 'com.google.android.gms:play-services:6.1.11'
      compile project(':facebook')
      compile files('libs/android-support-multidex.jar')
      compile files('libs/aws-android-sdk-1.6.0-debug.jar')
      compile files('libs/FlurryAnalytics_3.3.2.jar')
   }
  </code></pre>
  
  <p>I haven't changed any code in the xml file or the Fragment class that previously worked in Eclipse.</p>