Moves a couple of the maximize mode classes to ash/common

ash/wm/maximize_mode/maximize_mode_window_manager.cc

Index: ash/wm/maximize_mode/maximize_mode_window_manager.cc
diff --git a/ash/wm/maximize_mode/maximize_mode_window_manager.cc b/ash/wm/maximize_mode/maximize_mode_window_manager.cc
index 1b9914da689bdb1ec9436f6acf01ee33f8336c1a..3a8386a51c12e0fec2b45c0fc7c79547a8ac16b8 100644
--- a/ash/wm/maximize_mode/maximize_mode_window_manager.cc
+++ b/ash/wm/maximize_mode/maximize_mode_window_manager.cc
@@ -73,7 +73,8 @@ void MaximizeModeWindowManager::AddWindow(aura::Window* window) {
   MaximizeAndTrackWindow(window);
 }
 
-void MaximizeModeWindowManager::WindowStateDestroyed(aura::Window* window) {
+void MaximizeModeWindowManager::WindowStateDestroyed(WmWindow* wm_window) {
+  aura::Window* window = WmWindowAura::GetAuraWindow(wm_window);
   // At this time ForgetWindow() should already have been called. If not,
   // someone else must have replaced the "window manager's state object".
   DCHECK(!window->HasObserver(this));
@@ -253,7 +254,8 @@ void MaximizeModeWindowManager::MaximizeAndTrackWindow(
 
   // We create and remember a maximize mode state which will attach itself to
   // the provided state object.
-  window_state_map_[window] = new MaximizeModeWindowState(window, this);
+  window_state_map_[window] =
+      new MaximizeModeWindowState(WmWindowAura::Get(window), this);
 }
 
 void MaximizeModeWindowManager::ForgetWindow(aura::Window* window) {
@@ -345,7 +347,8 @@ void MaximizeModeWindowManager::EnableBackdropBehindTopWindowOnEachDisplay(
         controller->GetRootWindow(), kShellWindowId_DefaultContainer);
     controller->workspace_controller()->SetMaximizeBackdropDelegate(
         std::unique_ptr<WorkspaceLayoutManagerBackdropDelegate>(
-            enable ? new WorkspaceBackdropDelegate(container) : NULL));
+            enable ? new WorkspaceBackdropDelegate(WmWindowAura::Get(container))
+                   : nullptr));
   }
 }