Improve WorkspaceWindowResizer::CompleteDrag() so that the function moves the window to a root windo

ash/display/screen_position_controller.cc

Index: ash/display/screen_position_controller.cc
diff --git a/ash/display/screen_position_controller.cc b/ash/display/screen_position_controller.cc
index 124b6d2eca05ab987df484dfaf1eb962ba3104aa..1deb4e20972d41538e558c7764390b1e35c9fd38 100644
--- a/ash/display/screen_position_controller.cc
+++ b/ash/display/screen_position_controller.cc
@@ -7,7 +7,6 @@
 #include "ash/display/display_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
-#include "ash/wm/coordinate_conversion.h"
 #include "ash/wm/system_modal_container_layout_manager.h"
 #include "ash/wm/window_properties.h"
 #include "ui/aura/client/activation_client.h"
@@ -24,8 +23,10 @@ namespace {
 
 // Move all transient children to |dst_root|, including the ones in
 // the child windows and transient children of the transient children.
-void MoveAllTransientChildrenToNewRoot(aura::RootWindow* dst_root,
-                                    aura::Window* window) {
+void MoveAllTransientChildrenToNewRoot(const gfx::Display& display,
+                                       aura::Window* window) {
+  aura::RootWindow* dst_root = Shell::GetInstance()->display_controller()->
+      GetRootWindowForDisplayId(display.id());
   aura::Window::Windows transient_children = window->transient_children();
   for (aura::Window::Windows::iterator iter = transient_children.begin();
        iter != transient_children.end(); ++iter) {
@@ -35,17 +36,16 @@ void MoveAllTransientChildrenToNewRoot(aura::RootWindow* dst_root,
     aura::Window* container = Shell::GetContainer(dst_root, container_id);
     gfx::Rect parent_bounds_in_screen = transient_child->GetBoundsInScreen();
     container->AddChild(transient_child);
-    transient_child->SetBoundsInScreen(parent_bounds_in_screen);
+    transient_child->SetBoundsInScreen(parent_bounds_in_screen, display);
 
     // Transient children may have transient children.
-    MoveAllTransientChildrenToNewRoot(dst_root,
-                                   transient_child);
+    MoveAllTransientChildrenToNewRoot(display, transient_child);
   }
   // Move transient children of the child windows if any.
   aura::Window::Windows children = window->children();
   for (aura::Window::Windows::iterator iter = children.begin();
        iter != children.end(); ++iter)
-    MoveAllTransientChildrenToNewRoot(dst_root, *iter);
+    MoveAllTransientChildrenToNewRoot(display, *iter);
 }
 
 }  // namespace
@@ -78,9 +78,10 @@ void ScreenPositionController::ConvertPointFromScreen(
   aura::Window::ConvertPointToTarget(root, window, point);
 }
 
-void ScreenPositionController::SetBounds(
-    aura::Window* window,
-    const gfx::Rect& bounds) {
+void ScreenPositionController::SetBounds(aura::Window* window,
+                                         const gfx::Rect& bounds,
+                                         const gfx::Display& display) {
+  DCHECK_NE(-1, display.id());
   if (!DisplayController::IsExtendedDesktopEnabled() ||
       !window->parent()->GetProperty(internal::kUsesScreenCoordinatesKey)) {
     window->SetBounds(bounds);
@@ -90,7 +91,9 @@ void ScreenPositionController::SetBounds(
   // Don't move a transient windows to other root window.
   // It moves when its transient_parent moves.
   if (!window->transient_parent()) {
-    aura::RootWindow* dst_root = wm::GetRootWindowMatching(bounds);
+    aura::RootWindow* dst_root =
+        Shell::GetInstance()->display_controller()->GetRootWindowForDisplayId(
+            display.id());
     aura::Window* dst_container = NULL;
     if (dst_root != window->GetRootWindow()) {
       int container_id = window->parent()->id();
@@ -116,7 +119,7 @@ void ScreenPositionController::SetBounds(
 
       dst_container->AddChild(window);
 
-      MoveAllTransientChildrenToNewRoot(dst_root, window);
+      MoveAllTransientChildrenToNewRoot(display, window);
 
       // Restore focused/active window.
       if (tracker.Contains(focused))