Converts DockedWindowLayoutManager to common ash/wm types

ash/root_window_controller.cc

Index: ash/root_window_controller.cc
diff --git a/ash/root_window_controller.cc b/ash/root_window_controller.cc
index 12d433c839d1b0697e4aaf2f67235c8f8592b765..9e5108e0b0fd60a395a9f87af1b5c618ddd76cbd 100644
--- a/ash/root_window_controller.cc
+++ b/ash/root_window_controller.cc
@@ -33,6 +33,7 @@
 #include "ash/touch/touch_hud_projection.h"
 #include "ash/touch/touch_observer_hud.h"
 #include "ash/wm/always_on_top_controller.h"
+#include "ash/wm/aura/aura_layout_manager_adapter.h"
 #include "ash/wm/aura/wm_window_aura.h"
 #include "ash/wm/common/workspace/workspace_layout_manager_delegate.h"
 #include "ash/wm/dock/docked_window_layout_manager.h"
@@ -810,9 +811,10 @@ void RootWindowController::InitLayoutManagers() {
 
   // Create Docked windows layout manager
   aura::Window* docked_container = GetContainer(kShellWindowId_DockedContainer);

[varkha, 2016/04/21 17:46:55]

Would it make sense to have WmWindow* docked_container =
wm::WmWindowAura::Get(Getcontainer(id)) here and use that below?
Also could wm::WmWindowAura::Get() ever fail in otherwise non-fatal scenario?

[sky, 2016/04/21 18:03:04]

Done.
No. The only potentially bad scenario is if someone calls WmWindowAura::Get()
after the aura::Window properties have been cleared (meaning part way through
the destructor). Other code has this restriction too (such as WindowState), so
I'm hoping it won't come up in practice.

-  docked_layout_manager_ =
-      new DockedWindowLayoutManager(docked_container, workspace_controller());
-  docked_container->SetLayoutManager(docked_layout_manager_);
+  docked_layout_manager_ = new DockedWindowLayoutManager(
+      wm::WmWindowAura::Get(docked_container), workspace_controller());
+  wm::WmWindowAura::Get(docked_container)
+      ->SetLayoutManager(base::WrapUnique(docked_layout_manager_));
 
   // Installs SnapLayoutManager to containers who set the
   // |kSnapsChildrenToPhysicalPixelBoundary| property.