Launch app from the display where it is clicked

Changes:
We fixed this for shelf before
(https://codereview.chromium.org/2894743002), but not for
app launcher which results in inconsistent behavior. So
fix this for launcher as well.

Bug: 850335
Change-Id: I19849658ad0617fe7326895b58efd72261eb8a8c
Reviewed-on: https://chromium-review.googlesource.com/1091277Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565429}

chrome/browser/ui/app_list/app_list_controller_impl.cc

@@ -98,14 +98,13 @@ void AppListControllerDelegateImpl::ActivateApp(
   // Platform apps treat activations as a launch. The app can decide whether to
   // show a new window or focus an existing window as it sees fit.
   if (extension->is_platform_app()) {
-    LaunchApp(profile, extension, source, event_flags,
-              display::kInvalidDisplayId);
+    LaunchApp(profile, extension, source, event_flags, GetAppListDisplayId());
     return;
   }
 
   ChromeLauncherController::instance()->ActivateApp(
       extension->id(), AppListSourceToLaunchSource(source), event_flags,
-      display::kInvalidDisplayId);
+      GetAppListDisplayId());
 
   if (!IsHomeLauncherEnabledInTabletMode())
     DismissView();