WorkspaceLayoutManager backdrop should fill entire region.

ash/wm/maximize_mode/workspace_backdrop_delegate.cc

 // Copyright 2014 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 "ash/wm/maximize_mode/workspace_backdrop_delegate.h"
 
 #include "ash/wm/window_animations.h"
 #include "ash/wm/window_util.h"
 #include "base/auto_reset.h"
 #include "ui/aura/window.h"
@@ skipping 73 matching lines @@
 void WorkspaceBackdropDelegate::OnWindowStackingChanged(aura::Window* window) {
   RestackBackdrop();
 }
 
 void WorkspaceBackdropDelegate::OnPostWindowStateTypeChange(
     wm::WindowState* window_state,
     wm::WindowStateType old_type) {
   RestackBackdrop();
 }
 
+void WorkspaceBackdropDelegate::OnDisplayWorkAreaInsetsChanged() {
+  AdjustToContainerBounds();
+}
+
 void WorkspaceBackdropDelegate::RestackBackdrop() {
   // Avoid recursive calls.
   if (in_restacking_)
     return;
 
   aura::Window* window = GetCurrentTopWindow();
   if (!window) {
     // Hide backdrop since no suitable window was found.
     background_->Hide();
     return;
@@ skipping 43 matching lines @@
 
 void WorkspaceBackdropDelegate::Show() {
   background_->GetNativeView()->layer()->SetOpacity(0.0f);
   background_->Show();
   ui::ScopedLayerAnimationSettings settings(
       background_->GetNativeView()->layer()->GetAnimator());
   background_->GetNativeView()->layer()->SetOpacity(kBackdropOpacity);
 }
 
 }  // namespace ash