Draw web content area correctly on a phantom window for window dragging

ash/wm/workspace/workspace_window_resizer.cc

 // 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 "ash/wm/workspace/workspace_window_resizer.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "ash/display/display_controller.h"
@@ skipping 54 matching lines @@
 // static
 const int WorkspaceWindowResizer::kMinOnscreenSize = 20;
 
 // static
 const int WorkspaceWindowResizer::kMinOnscreenHeight = 32;
 
 WorkspaceWindowResizer::~WorkspaceWindowResizer() {
   Shell* shell = Shell::GetInstance();
   shell->display_controller()->set_dont_warp_mouse(false);
   shell->cursor_manager()->UnlockCursor();
+
+  // Delete phantom controllers first so that they will never see the deleted
+  // |layer_|.
+  snap_phantom_window_controller_.reset();
+  drag_phantom_window_controller_.reset();
+
+  if (layer_)
+    wm::DeepDeleteLayers(layer_);
 }
 
 // static
 WorkspaceWindowResizer* WorkspaceWindowResizer::Create(
     aura::Window* window,
     const gfx::Point& location_in_parent,
     int window_component,
     const std::vector<aura::Window*>& attached_windows) {
   Details details(window, location_in_parent, window_component);
   return details.is_resizable ?
@@ skipping 132 matching lines @@
 
 WorkspaceWindowResizer::WorkspaceWindowResizer(
     const Details& details,
     const std::vector<aura::Window*>& attached_windows)
     : details_(details),
       attached_windows_(attached_windows),
       did_move_or_resize_(false),
       total_min_(0),
       total_initial_size_(0),
       snap_type_(SNAP_NONE),
-      num_mouse_moves_since_bounds_change_(0) {
+      num_mouse_moves_since_bounds_change_(0),
+      layer_(NULL) {
   DCHECK(details_.is_resizable);
 
   Shell* shell = Shell::GetInstance();
   shell->cursor_manager()->LockCursor();
 
   // The pointer should be confined in one display during resizing a window
   // because the window cannot span two displays at the same time anyway. The
   // exception is window/tab dragging operation. During that operation,
   // |dont_warp_mouse_| should be set to false so that the user could move a
   // window/tab to another display.
@@ skipping 232 matching lines @@
 
   if (fraction_in_another_window > 0) {
     if (!drag_phantom_window_controller_.get()) {
       drag_phantom_window_controller_.reset(
           new PhantomWindowController(window()));
       drag_phantom_window_controller_->set_style(
           PhantomWindowController::STYLE_WINDOW);
       // Always show the drag phantom on the |another_root| window.
       drag_phantom_window_controller_->SetDestinationDisplay(
           gfx::Screen::GetDisplayMatching(another_root->GetBoundsInScreen()));
+      if (!layer_)
+        RecreateWindowLayers();
+      drag_phantom_window_controller_->set_layer(layer_);
       drag_phantom_window_controller_->Show(bounds_in_screen);
     } else {
       // No animation.
       drag_phantom_window_controller_->SetBounds(bounds_in_screen);
     }
     drag_phantom_window_controller_->SetOpacity(phantom_opacity);
     window()->layer()->SetOpacity(window_opacity);
   } else {
     drag_phantom_window_controller_.reset();
     window()->layer()->SetOpacity(1.0f);
@@ skipping 72 matching lines @@
     return SNAP_RIGHT_EDGE;
   return SNAP_NONE;
 }
 
 bool WorkspaceWindowResizer::ShouldAllowMouseWarp() const {
   return (details_.window_component == HTCAPTION) &&
       (window()->GetProperty(aura::client::kModalKey) == ui::MODAL_TYPE_NONE) &&
       (window()->type() == aura::client::WINDOW_TYPE_NORMAL);
 }
 
+void WorkspaceWindowResizer::RecreateWindowLayers() {
+  DCHECK(!layer_);
+  layer_ = wm::RecreateWindowLayers(window());
+  // Place the layer at (0, 0) of the PhantomWindowController's window.
+  gfx::Rect layer_bounds = layer_->bounds();
+  layer_bounds.set_origin(gfx::Point(0, 0));
+  layer_->SetBounds(layer_bounds);
+  layer_->SetVisible(false);
+  // Detach it from the current container.
+  layer_->parent()->Remove(layer_);
+}
+
 }  // namespace internal
 }  // namespace ash