Listen to Display reconfiguration and notify DisplayObservers on Mac.

content/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
 
@@ skipping 477 matching lines @@
                   initWithRenderWidgetHostViewMac:this] autorelease];
 
   background_layer_.reset([[CALayer alloc] init]);
   [background_layer_
       setBackgroundColor:CGColorGetConstantColor(kCGColorWhite)];
   [background_layer_ setGeometryFlipped:YES];
   [background_layer_ setContentsGravity:kCAGravityTopLeft];
   [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;
 
   UnlockMouse();
 
   // Make sure that the layer doesn't reach into the now-invalid object.
   DestroyCompositedIOSurfaceAndLayer();
   DestroySoftwareLayer();
 
@@ skipping 1779 matching lines @@
 void RenderWidgetHostViewMac::AcceleratedLayerDidDrawFrame(bool succeeded) {
   if (!render_widget_host_)
     return;
 
   SendPendingLatencyInfoToHost();
   SendPendingSwapAck();
   if (!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 ---------------------------------------------------
 
 @implementation RenderWidgetHostViewCocoa
 @synthesize selectedRange = selectedRange_;
 @synthesize suppressNextEscapeKeyUp = suppressNextEscapeKeyUp_;
 @synthesize markedRange = markedRange_;
 
 - (id)initWithRenderWidgetHostViewMac:(RenderWidgetHostViewMac*)r {
@@ skipping 1662 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end