Some minor UI refinements

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=135353593

library/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java

@@ -184,6 +184,14 @@ public final class SimpleExoPlayer implements ExoPlayer {
   }
 
   /**
+   * Clears any {@link Surface}, {@link SurfaceHolder}, {@link SurfaceView} or {@link TextureView}
+   * currently set on the player.
+   */
+  public void clearVideoSurface() {
+    setVideoSurface(null);
+  }
+
+  /**
    * Sets the {@link Surface} onto which video will be rendered. The caller is responsible for
    * tracking the lifecycle of the surface, and must clear the surface by calling
    * {@code setVideoSurface(null)} if the surface is destroyed.
@@ -240,6 +248,9 @@ public final class SimpleExoPlayer implements ExoPlayer {
     if (textureView == null) {
       setVideoSurfaceInternal(null);
     } else {
+      if (textureView.getSurfaceTextureListener() != null) {
+        Log.w(TAG, "Replacing existing SurfaceTextureListener.");
+      }
       SurfaceTexture surfaceTexture = textureView.getSurfaceTexture();
       setVideoSurfaceInternal(surfaceTexture == null ? null : new Surface(surfaceTexture));
       textureView.setSurfaceTextureListener(componentListener);
@@ -593,13 +604,17 @@ public final class SimpleExoPlayer implements ExoPlayer {
   }
 
   private void removeSurfaceCallbacks() {
-    if (this.textureView != null) {
-      this.textureView.setSurfaceTextureListener(null);
-      this.textureView = null;
+    if (textureView != null) {
+      if (textureView.getSurfaceTextureListener() != componentListener) {
+        Log.w(TAG, "SurfaceTextureListener already unset or replaced.");
+      } else {
+        textureView.setSurfaceTextureListener(null);
+      }
+      textureView = null;
     }
-    if (this.surfaceHolder != null) {
-      this.surfaceHolder.removeCallback(componentListener);
-      this.surfaceHolder = null;
+    if (surfaceHolder != null) {
+      surfaceHolder.removeCallback(componentListener);
+      surfaceHolder = null;
     }
   }
 

library/src/main/java/com/google/android/exoplayer2/ui/PlaybackControlView.java

@@ -140,6 +140,9 @@ public class PlaybackControlView extends FrameLayout {
    * @param player the {@code ExoPlayer} to control.
    */
   public void setPlayer(ExoPlayer player) {
+    if (this.player == player) {
+      return;
+    }
     if (this.player != null) {
       this.player.removeListener(componentListener);
     }

library/src/main/java/com/google/android/exoplayer2/ui/SimpleExoPlayerView.java

@@ -112,6 +112,9 @@ public final class SimpleExoPlayerView extends FrameLayout {
    * @param player The {@link SimpleExoPlayer} to use.
    */
   public void setPlayer(SimpleExoPlayer player) {
+    if (this.player == player) {
+      return;
+    }
     if (this.player != null) {
       this.player.setTextOutput(null);
       this.player.setVideoListener(null);
@@ -131,7 +134,9 @@ public final class SimpleExoPlayerView extends FrameLayout {
     } else {
       shutterView.setVisibility(VISIBLE);
     }
-    setUseController(useController);
+    if (useController) {
+      controller.setPlayer(player);
+    }
   }
 
   /**
@@ -142,6 +147,9 @@ public final class SimpleExoPlayerView extends FrameLayout {
    * @param useController If {@code false} the playback control is never used.
    */
   public void setUseController(boolean useController) {
+    if (this.useController == useController) {
+      return;
+    }
     this.useController = useController;
     if (useController) {
       controller.setPlayer(player);