Have OobeUI handle display observation

chrome/browser/ui/webui/chromeos/login/oobe_ui.cc

Index: chrome/browser/ui/webui/chromeos/login/oobe_ui.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/oobe_ui.cc b/chrome/browser/ui/webui/chromeos/login/oobe_ui.cc
index c7941c628158b9a0336d4ff09bfcc470ab02b283..67a09180f5bac8864c7eeb94d27566b619f847ae 100644
--- a/chrome/browser/ui/webui/chromeos/login/oobe_ui.cc
+++ b/chrome/browser/ui/webui/chromeos/login/oobe_ui.cc
@@ -78,6 +78,8 @@
 #include "content/public/common/content_switches.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/base/webui/web_ui_util.h"
+#include "ui/display/display.h"
+#include "ui/display/screen.h"
 
 namespace chromeos {
 
@@ -331,10 +333,13 @@ OobeUI::OobeUI(content::WebUI* web_ui, const GURL& url)
   // TabHelper is required for OOBE webui to make webview working on it.
   content::WebContents* contents = web_ui->GetWebContents();
   extensions::TabHelper::CreateForWebContents(contents);
+
+  display::Screen::GetScreen()->AddObserver(this);
 }
 
 OobeUI::~OobeUI() {
   network_dropdown_handler_->RemoveObserver(GetView<ErrorScreenHandler>());
+  display::Screen::GetScreen()->RemoveObserver(this);
   if (ash_util::IsRunningInMash()) {
     // TODO: Ash needs to expose screen dimming api. See
     // http://crbug.com/646034.
@@ -435,6 +440,23 @@ UserBoardView* OobeUI::GetUserBoardView() {
   return GetView<UserBoardScreenHandler>();
 }
 
+void OobeUI::OnDisplayAdded(const display::Display& new_display) {}
+
+void OobeUI::OnDisplayRemoved(const display::Display& old_display) {}
+
+void OobeUI::OnDisplayMetricsChanged(const display::Display& display,
+                                     uint32_t changed_metrics) {
+  display::Display primary_display =
+      display::Screen::GetScreen()->GetPrimaryDisplay();
+  if (display.id() != primary_display.id() ||
+      !(changed_metrics & DISPLAY_METRIC_BOUNDS)) {
+    return;
+  }
+
+  const gfx::Size& size = primary_display.size();
+  GetCoreOobeView()->SetClientAreaSize(size.width(), size.height());
+}
+
 void OobeUI::OnShutdownPolicyChanged(bool reboot_on_shutdown) {
   core_handler_->UpdateShutdownAndRebootVisibility(reboot_on_shutdown);
 }