customtabs: Prevent the app menu window from leaking when finishing the activity.

chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java
index f0649dbeb6734b4d0d30227468a1deb47814b86e..d75bcacdf503bd1cf6ea2d453854ed8fc287fc1d 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java
@@ -50,6 +50,7 @@ import org.chromium.chrome.browser.ChromeSwitches;
 import org.chromium.chrome.browser.ChromeTabbedActivity;
 import org.chromium.chrome.browser.IntentHandler;
 import org.chromium.chrome.browser.TabsOpenedFromExternalAppTest;
+import org.chromium.chrome.browser.appmenu.AppMenuHandler;
 import org.chromium.chrome.browser.document.ChromeLauncherActivity;
 import org.chromium.chrome.browser.prerender.ExternalPrerenderHandler;
 import org.chromium.chrome.browser.profiles.Profile;
@@ -138,6 +139,18 @@ public class CustomTabActivityTest extends CustomTabActivityTestBase {
     @Override
     protected void tearDown() throws Exception {
         mTestServer.stopAndDestroyServer();
+
+        // finish() is called on a non-UI thread by the testing harness. Must hide the menu
+        // first, otherwise the UI is manipulated on a non-UI thread.
+        ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+            @Override
+            public void run() {
+                if (mActivity == null) return;
+                AppMenuHandler handler = mActivity.getAppMenuHandler();
+                if (handler != null) handler.hideAppMenu();
+            }
+        });
+
         super.tearDown();
     }