Inform LoginDisplayHost observers about view bounds changes

This cl informes LoginDisplayHost observers about
view bounds changes in LoginDisplayHostWebUI. The corresponding
implementation for LoginDisplayHostMojo has already been implemented.

Bug: 1145668
Change-Id: Ibfae96eb43be77dbcf7c37ff8a5d14b0bc532365
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2519859Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Commit-Queue: Yilkal Abe <yilkal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824943}

chrome/browser/chromeos/login/ui/login_display_host_webui.cc

@@ -833,6 +833,12 @@ void LoginDisplayHostWebUI::OnWidgetDestroying(views::Widget* widget) {
   login_view_ = nullptr;
 }
 
+void LoginDisplayHostWebUI::OnWidgetBoundsChanged(views::Widget* widget,
+                                                  const gfx::Rect& new_bounds) {
+  for (auto& observer : observers_)
+    observer.WebDialogViewBoundsChanged(new_bounds);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // LoginDisplayHostWebUI, ash::MultiUserWindowManagerObserver:
 void LoginDisplayHostWebUI::OnUserSwitchAnimationFinished() {
@@ -1028,10 +1034,14 @@ bool LoginDisplayHostWebUI::HasUserPods() {
   return false;
 }
 
-void LoginDisplayHostWebUI::AddObserver(LoginDisplayHost::Observer* observer) {}
+void LoginDisplayHostWebUI::AddObserver(LoginDisplayHost::Observer* observer) {
+  observers_.AddObserver(observer);
+}
 
 void LoginDisplayHostWebUI::RemoveObserver(
-    LoginDisplayHost::Observer* observer) {}
+    LoginDisplayHost::Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
 
 void LoginDisplayHostWebUI::PlayStartupSoundIfPossible() {
   if (!need_to_play_startup_sound_ || oobe_startup_sound_played_)

chrome/browser/chromeos/login/ui/login_display_host_webui.h

@@ -14,6 +14,7 @@
 #include "ash/public/cpp/multi_user_window_manager_observer.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "base/trace_event/trace_event.h"
 #include "chrome/browser/chromeos/login/existing_user_controller.h"
 #include "chrome/browser/chromeos/login/oobe_configuration.h"
@@ -133,6 +134,8 @@ class LoginDisplayHostWebUI : public LoginDisplayHostCommon,
 
   // views::WidgetObserver:
   void OnWidgetDestroying(views::Widget* widget) override;
+  void OnWidgetBoundsChanged(views::Widget* widget,
+                             const gfx::Rect& new_bounds) override;
 
   // ash::MultiUserWindowManagerObserver:
   void OnUserSwitchAnimationFinished() override;
@@ -253,6 +256,8 @@ class LoginDisplayHostWebUI : public LoginDisplayHostCommon,
   // True if we need to play startup sound when audio device becomes available.
   bool need_to_play_startup_sound_ = false;
 
+  base::ObserverList<LoginDisplayHost::Observer> observers_;
+
   base::WeakPtrFactory<LoginDisplayHostWebUI> weak_factory_{this};
 
   DISALLOW_COPY_AND_ASSIGN(LoginDisplayHostWebUI);