Listen to Display reconfiguration and notify DisplayObservers on Mac.

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index bb24a63ae1ca6c7aa9190df4cf459abe1ff7541f..55ed9007f4dd04842d2f9a7af6ee344160f4ab21 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -495,10 +495,14 @@ RenderWidgetHostViewMac::RenderWidgetHostViewMac(RenderWidgetHost* widget)
   [cocoa_view_ setLayer:background_layer_];
   [cocoa_view_ setWantsLayer:YES];
 
+  gfx::Screen::GetScreenFor(cocoa_view_)->AddObserver(this);
+
   render_widget_host_->SetView(this);
 }
 
 RenderWidgetHostViewMac::~RenderWidgetHostViewMac() {
+  gfx::Screen::GetScreenFor(cocoa_view_)->RemoveObserver(this);
+
   // This is being called from |cocoa_view_|'s destructor, so invalidate the
   // pointer.
   cocoa_view_ = nil;
@@ -2298,6 +2302,24 @@ void RenderWidgetHostViewMac::AcceleratedLayerDidDrawFrame(bool succeeded) {
     GotAcceleratedCompositingError();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// gfx::DisplayObserver, public:
+
+void RenderWidgetHostViewMac::OnDisplayAdded(const gfx::Display& display) {
+}
+
+void RenderWidgetHostViewMac::OnDisplayRemoved(const gfx::Display& display) {
+}
+
+void RenderWidgetHostViewMac::OnDisplayMetricsChanged(
+    const gfx::Display& display, uint32_t metrics) {
+  gfx::Screen* screen = gfx::Screen::GetScreenFor(cocoa_view_);
+  if (display.id() != screen->GetDisplayNearestWindow(cocoa_view_).id())
+    return;
+
+  UpdateScreenInfo(cocoa_view_);
+}
+
 }  // namespace content
 
 // RenderWidgetHostViewCocoa ---------------------------------------------------