Move build*DataSourceFactory methods to the DemoApplication class for easy customization.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=134414869

demo/build.gradle

@@ -39,14 +39,14 @@ android {
 
     productFlavors {
         demo
-        demo_ext
+        demoExt
     }
 }
 
 dependencies {
     compile project(':library')
-    demo_extCompile project(path: ':extension-ffmpeg')
-    demo_extCompile project(path: ':extension-flac')
-    demo_extCompile project(path: ':extension-opus')
-    demo_extCompile project(path: ':extension-vp9')
+    demoExtCompile project(path: ':extension-ffmpeg')
+    demoExtCompile project(path: ':extension-flac')
+    demoExtCompile project(path: ':extension-opus')
+    demoExtCompile project(path: ':extension-vp9')
 }

demo/src/main/java/com/google/android/exoplayer2/demo/DemoApplication.java

@@ -16,9 +16,33 @@
 package com.google.android.exoplayer2.demo;
 
 import android.app.Application;
+import com.google.android.exoplayer2.upstream.DataSource;
+import com.google.android.exoplayer2.upstream.DefaultBandwidthMeter;
+import com.google.android.exoplayer2.upstream.DefaultDataSourceFactory;
+import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
+import com.google.android.exoplayer2.upstream.HttpDataSource;
+import com.google.android.exoplayer2.util.Util;
 
 /**
  * Placeholder application to facilitate overriding Application methods for debugging and testing.
  */
 public class DemoApplication extends Application {
+
+  protected String userAgent;
+
+  @Override
+  public void onCreate() {
+    super.onCreate();
+    userAgent = Util.getUserAgent(this, "ExoPlayerDemo");
+  }
+
+  DataSource.Factory buildDataSourceFactory(DefaultBandwidthMeter bandwidthMeter) {
+    return new DefaultDataSourceFactory(this, bandwidthMeter,
+        buildHttpDataSourceFactory(bandwidthMeter));
+  }
+
+  HttpDataSource.Factory buildHttpDataSourceFactory(DefaultBandwidthMeter bandwidthMeter) {
+    return new DefaultHttpDataSourceFactory(userAgent, bandwidthMeter);
+  }
+
 }

demo/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -65,8 +65,6 @@ import com.google.android.exoplayer2.ui.PlaybackControlView;
 import com.google.android.exoplayer2.ui.SimpleExoPlayerView;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DefaultBandwidthMeter;
-import com.google.android.exoplayer2.upstream.DefaultDataSourceFactory;
-import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
 import com.google.android.exoplayer2.upstream.HttpDataSource;
 import com.google.android.exoplayer2.util.Util;
 import java.net.CookieHandler;
@@ -109,7 +107,6 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
   private TextView debugTextView;
   private Button retryButton;
 
-  private String userAgent;
   private DataSource.Factory mediaDataSourceFactory;
   private SimpleExoPlayer player;
   private MappingTrackSelector trackSelector;
@@ -128,7 +125,6 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
   public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     shouldAutoPlay = true;
-    userAgent = Util.getUserAgent(this, "ExoPlayerDemo");
     mediaDataSourceFactory = buildDataSourceFactory(true);
     mainHandler = new Handler();
     if (CookieHandler.getDefault() != DEFAULT_COOKIE_MANAGER) {
@@ -378,8 +374,8 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
    * @return A new DataSource factory.
    */
   private DataSource.Factory buildDataSourceFactory(boolean useBandwidthMeter) {
-    return new DefaultDataSourceFactory(this, useBandwidthMeter ? BANDWIDTH_METER : null,
-        buildHttpDataSourceFactory(useBandwidthMeter));
+    return ((DemoApplication) getApplication())
+        .buildDataSourceFactory(useBandwidthMeter ? BANDWIDTH_METER : null);
   }
 
   /**
@@ -390,7 +386,8 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
    * @return A new HttpDataSource factory.
    */
   private HttpDataSource.Factory buildHttpDataSourceFactory(boolean useBandwidthMeter) {
-    return new DefaultHttpDataSourceFactory(userAgent, useBandwidthMeter ? BANDWIDTH_METER : null);
+    return ((DemoApplication) getApplication())
+        .buildHttpDataSourceFactory(useBandwidthMeter ? BANDWIDTH_METER : null);
   }
 
   // ExoPlayer.EventListener implementation