Fix issue with microphone button doing nothing in search widget.

The new LocationBarVoiceRecognitionHandler was using Tab's #getActivity
instead of using WindowAndroid's #getActivity. In the search widget,
Tab's getActivity returned null and exited #startVoiceRecognition
early.

This fix just gets the WindowAndroid from the Tab first and then uses
its activity and all is well.

Bug: 828309
Change-Id: I05b68b0228d1c5f962ee1ee2fa23675ccaa5b6db
Reviewed-on: https://chromium-review.googlesource.com/992992Reviewed-by: Maria Khomenko <mariakhomenko@chromium.org>
Commit-Queue: Troy Hildebrandt <thildebr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547750}

chrome/android/java/src/org/chromium/chrome/browser/omnibox/LocationBarVoiceRecognitionHandler.java

@@ -201,10 +201,11 @@ public class LocationBarVoiceRecognitionHandler {
     public void startVoiceRecognition(@VoiceInteractionSource int source) {
         Tab tab = getCurrentTab();
         if (tab == null) return;
-        Activity activity = tab.getActivity();
+        WindowAndroid windowAndroid = tab.getWindowAndroid();
+        if (windowAndroid == null) return;
+        Activity activity = windowAndroid.getActivity().get();
         if (activity == null) return;
 
-        WindowAndroid windowAndroid = tab.getWindowAndroid();
         if (!windowAndroid.hasPermission(Manifest.permission.RECORD_AUDIO)) {
             if (windowAndroid.canRequestPermission(Manifest.permission.RECORD_AUDIO)) {
                 WindowAndroid.PermissionCallback callback = new WindowAndroid.PermissionCallback() {