[PiP Android API] Finish activity when exiting picture in picture mode.

Bug: 964380
Change-Id: Ifd8883adb8f93a27694046f8c13a5b89545097c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1759229Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: Jazz Xu <jazzhsu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688240}

chrome/android/java/src/org/chromium/chrome/browser/media/PictureInPictureActivity.java

@@ -8,6 +8,7 @@ import android.annotation.SuppressLint;
 import android.app.ActivityManager;
 import android.content.Context;
 import android.content.Intent;
+import android.content.res.Configuration;
 
 import org.chromium.base.ContextUtils;
 import org.chromium.base.annotations.CalledByNative;
@@ -99,6 +100,12 @@ public class PictureInPictureActivity extends AsyncInitializationActivity {
         sTabObserver = null;
     }
 
+    @Override
+    public void onPictureInPictureModeChanged(
+            boolean isInPictureInPictureMode, Configuration newConfig) {
+        if (!isInPictureInPictureMode) this.finish();
+    }
+
     @Override
     protected ActivityWindowAndroid createWindowAndroid() {
         return new ActivityWindowAndroid(this);