Call releaseSession() when "stop casting" button click

Bug: 147856563
Test: make -j42 RunSettingsRoboTests
Change-Id: Id096b84af4d0c98cf6a24a17e7bd5723d1670c24

src/com/android/settings/panel/MediaOutputPanel.java

@@ -186,6 +186,7 @@ public class MediaOutputPanel implements PanelContent, LocalMediaManager.DeviceC
 
     @Override
     public void onClickCustomizedButton() {
+        mLocalMediaManager.releaseSession();
     }
 
     @Override

tests/robotests/src/com/android/settings/panel/MediaOutputPanelTest.java

@@ -236,4 +236,11 @@ public class MediaOutputPanelTest {
         assertThat(mPanel.getSubTitle()).isEqualTo(mContext.getText(
                 R.string.media_output_panel_title));
     }
+
+    @Test
+    public void onClickCustomizedButton_shouldReleaseSession() {
+        mPanel.onClickCustomizedButton();
+
+        verify(mLocalMediaManager).releaseSession();
+    }
 }