chromeos: fix use of uninitialized value in DisplayManager

DisplayManager's constructor is called from WindowServer's
constructor. This means DisplayManager shouldn't call to WindowServer,
else we get use of unitialized values like this.

BUG=822246
TEST=covered by tests

Change-Id: I296911502021a135276a9db49b98927efea95618
Reviewed-on: https://chromium-review.googlesource.com/963831Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543437}

services/ui/ws/display_manager.cc

@@ -37,11 +37,11 @@
 namespace ui {
 namespace ws {
 
-DisplayManager::DisplayManager(WindowServer* window_server)
+DisplayManager::DisplayManager(WindowServer* window_server, bool is_hosting_viz)
     : window_server_(window_server),
       cursor_location_manager_(std::make_unique<CursorLocationManager>()) {
 #if defined(OS_CHROMEOS)
-  if (window_server->is_hosting_viz()) {
+  if (is_hosting_viz) {
     // TODO: http://crbug.com/701468 fix function key preferences and sticky
     // keys.
     ui::EventRewriterChromeOS::Delegate* delegate = nullptr;

services/ui/ws/display_manager.h

@@ -34,7 +34,7 @@ class WindowServer;
 // those that do.
 class DisplayManager : public display::ScreenManagerDelegate {
  public:
-  explicit DisplayManager(WindowServer* window_server);
+  DisplayManager(WindowServer* window_server, bool is_hosting_viz);
   ~DisplayManager() override;
 
   // Called once WindowServer::display_creation_config() has been determined.

services/ui/ws/window_server.cc

@@ -135,7 +135,7 @@ struct WindowServer::CurrentDragLoopState {
 WindowServer::WindowServer(WindowServerDelegate* delegate, bool should_host_viz)
     : delegate_(delegate),
       next_client_id_(kWindowServerClientId + 1),
-      display_manager_(std::make_unique<DisplayManager>(this)),
+      display_manager_(std::make_unique<DisplayManager>(this, should_host_viz)),
       current_operation_(nullptr),
       in_destructor_(false),
       next_wm_change_id_(0),