Fix leaked external surface when several EME videos coexist

android_webview/java/src/org/chromium/android_webview/ExternalVideoSurfaceContainer.java

Index: android_webview/java/src/org/chromium/android_webview/ExternalVideoSurfaceContainer.java
diff --git a/android_webview/java/src/org/chromium/android_webview/ExternalVideoSurfaceContainer.java b/android_webview/java/src/org/chromium/android_webview/ExternalVideoSurfaceContainer.java
index 86f75808ac68715b2b2459232553c2a65cd86df6..e0e1f6657bf19d9a7d1826b210ce17cb8a36e9c5 100644
--- a/android_webview/java/src/org/chromium/android_webview/ExternalVideoSurfaceContainer.java
+++ b/android_webview/java/src/org/chromium/android_webview/ExternalVideoSurfaceContainer.java
@@ -118,9 +118,7 @@ public class ExternalVideoSurfaceContainer implements SurfaceHolder.Callback {
     protected void requestExternalVideoSurface(int playerId) {
         if (mPlayerId == playerId) return;
 
-        if (mPlayerId == INVALID_PLAYER_ID) {
-            setActiveContainer(this);
-        }
+        setActiveContainer(this);
 
         mPlayerId = playerId;
         initializeCurrentPositionOfSurfaceView();
@@ -169,6 +167,7 @@ public class ExternalVideoSurfaceContainer implements SurfaceHolder.Callback {
     }
 
     private void createSurfaceView() {
+        assert mSurfaceView == null;
         mSurfaceView = new NoPunchingSurfaceView(mContentViewCore.getContext());
         mSurfaceView.getHolder().addCallback(this);
         // SurfaceHoder.surfaceCreated() will be called after the SurfaceView is attached to