[CrOS] Initial rough cut of alt-tab window cycling UI.

A bit ugly, but mostly functional. I think most changes going forward
should be aesthetic, so this seems like a decent place for an initial
commit.

Enabled with --ash-enable-window-cycle-ui flag.

BUG=626111

Review-Url: https://codereview.chromium.org/2129773002
Cr-Commit-Position: refs/heads/master@{#406120}

ash/ash.gyp

@@ -340,6 +340,8 @@
       'common/wm/drag_details.h',
       'common/wm/focus_rules.cc',
       'common/wm/focus_rules.h',
+      'common/wm/forwarding_layer_delegate.cc',
+      'common/wm/forwarding_layer_delegate.h',
       'common/wm/fullscreen_window_finder.cc',
       'common/wm/fullscreen_window_finder.h',
       'common/wm/maximize_mode/maximize_mode_controller.cc',

ash/common/ash_switches.cc

@@ -75,6 +75,9 @@ const char kAshEnableSoftwareMirroring[] = "ash-enable-software-mirroring";
 // flag is removed.
 const char kAshEnableTouchViewTesting[] = "ash-enable-touch-view-testing";
 
+// Enables the window cycling UI (more visual feedback for alt-tab).
+const char kAshEnableWindowCycleUi[] = "ash-enable-window-cycle-ui";
+
 // Hides notifications that are irrelevant to Chrome OS device factory testing,
 // such as battery level updates.
 const char kAshHideNotificationsForFactory[] =

ash/common/ash_switches.h

@@ -37,6 +37,7 @@ ASH_EXPORT extern const char kAshDisableStableOverviewOrder[];
 ASH_EXPORT extern const char kAshEnableStableOverviewOrder[];
 ASH_EXPORT extern const char kAshEnableSoftwareMirroring[];
 ASH_EXPORT extern const char kAshEnableTouchViewTesting[];
+ASH_EXPORT extern const char kAshEnableWindowCycleUi[];
 ASH_EXPORT extern const char kAshHideNotificationsForFactory[];
 ASH_EXPORT extern const char kAshHostWindowBounds[];
 ASH_EXPORT extern const char kAshMaterialDesign[];

ash/common/wm/forwarding_layer_delegate.cc

+// Copyright 2016 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/common/wm/forwarding_layer_delegate.h"
+
+#include "ash/common/wm_window.h"
+#include "base/callback.h"
+#include "ui/compositor/layer.h"
+
+namespace ash {
+namespace wm {
+
+ForwardingLayerDelegate::ForwardingLayerDelegate(WmWindow* original_window,
+                                                 ui::LayerDelegate* delegate)
+    : original_window_(original_window), original_delegate_(delegate) {}
+
+ForwardingLayerDelegate::~ForwardingLayerDelegate() {}
+
+void ForwardingLayerDelegate::OnPaintLayer(const ui::PaintContext& context) {
+  if (!original_delegate_)
+    return;
+  // |original_delegate_| may have already been deleted or
+  // disconnected by this time. Check if |original_delegate_| is still
+  // used by the original_window tree, or skip otherwise.
+  if (IsDelegateValid(original_window_->GetLayer()))
+    original_delegate_->OnPaintLayer(context);
+  else
+    original_delegate_ = nullptr;
+}
+
+void ForwardingLayerDelegate::OnDelegatedFrameDamage(
+    const gfx::Rect& damage_rect_in_dip) {}
+
+void ForwardingLayerDelegate::OnDeviceScaleFactorChanged(
+    float device_scale_factor) {
+  // Don't tell the original delegate about device scale factor change
+  // on cloned layer because the original layer is still on the same display.
+}
+
+base::Closure ForwardingLayerDelegate::PrepareForLayerBoundsChange() {
+  return base::Closure();
+}
+
+bool ForwardingLayerDelegate::IsDelegateValid(ui::Layer* layer) const {
+  if (layer->delegate() == original_delegate_)
+    return true;
+  for (auto* child : layer->children()) {
+    if (IsDelegateValid(child))
+      return true;
+  }
+  return false;
+}
+
+}  // namespace wm
+}  // namespace ash

ash/common/wm/forwarding_layer_delegate.h

+// Copyright 2016 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.
+
+#ifndef ASH_COMMON_WM_FORWARDING_LAYER_DELEGATE_H_
+#define ASH_COMMON_WM_FORWARDING_LAYER_DELEGATE_H_
+
+#include "base/macros.h"
+#include "ui/compositor/layer_delegate.h"
+
+namespace ui {
+class Layer;
+}
+
+namespace ash {
+
+class WmWindow;
+
+namespace wm {
+
+// A layer delegate to paint the content of a recreated layer by delegating
+// the paint request to the original delegate. It checks if the original
+// delegate is still valid by traversing the original layers.
+class ForwardingLayerDelegate : public ui::LayerDelegate {
+ public:
+  ForwardingLayerDelegate(WmWindow* original_window,
+                          ui::LayerDelegate* delegate);
+  ~ForwardingLayerDelegate() override;
+
+ private:
+  bool IsDelegateValid(ui::Layer* layer) const;
+
+  // ui:LayerDelegate:
+  void OnPaintLayer(const ui::PaintContext& context) override;
+  void OnDelegatedFrameDamage(const gfx::Rect& damage_rect_in_dip) override;
+  void OnDeviceScaleFactorChanged(float device_scale_factor) override;
+  base::Closure PrepareForLayerBoundsChange() override;
+
+  WmWindow* original_window_;
+  ui::LayerDelegate* original_delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(ForwardingLayerDelegate);
+};
+
+}  // namespace wm
+}  // namespace ash
+
+#endif  // ASH_COMMON_WM_FORWARDING_LAYER_DELEGATE_H_

ash/wm/drag_window_controller.cc

@@ -6,7 +6,9 @@
 
 #include <algorithm>
 
+#include "ash/aura/wm_window_aura.h"
 #include "ash/common/shell_window_ids.h"
+#include "ash/common/wm/forwarding_layer_delegate.h"
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
@@ -28,61 +30,9 @@
 #include "ui/wm/core/window_util.h"
 
 namespace ash {
-namespace {
 
-// A layer delegate to paint the content of the recreaetd layers
-// by delegating the paint request to the original delegate.
-// It checks if the orignal delegate is still valid by traversing
-// the original layers.
-class DragWindowLayerDelegate : public ui::LayerDelegate {
- public:
-  DragWindowLayerDelegate(aura::Window* original_window,
-                          ui::LayerDelegate* delegate)
-      : original_window_(original_window), original_delegate_(delegate) {}
-  ~DragWindowLayerDelegate() override {}
-
- private:
-  // ui:LayerDelegate:
-  void OnPaintLayer(const ui::PaintContext& context) override {
-    if (!original_delegate_)
-      return;
-    // |original_delegate_| may have already been deleted or
-    // disconnected by this time. Check if |original_delegate_| is still
-    // used by the original_window tree, or skip otherwise.
-    if (IsDelegateValid(original_window_->layer()))
-      original_delegate_->OnPaintLayer(context);
-    else
-      original_delegate_ = nullptr;
-  }
-  void OnDelegatedFrameDamage(const gfx::Rect& damage_rect_in_dip) override {}
-  void OnDeviceScaleFactorChanged(float device_scale_factor) override {
-    // Don't tell the original delegate about device scale factor change
-    // on cloned layer because the original layer is still on the same display.
-  }
-  base::Closure PrepareForLayerBoundsChange() override {
-    return base::Closure();
-  }
-
-  bool IsDelegateValid(ui::Layer* layer) {
-    if (layer->delegate() == original_delegate_)
-      return true;
-    for (auto* child : layer->children()) {
-      if (IsDelegateValid(child))
-        return true;
-    }
-    return false;
-  }
-
-  aura::Window* original_window_;
-  ui::LayerDelegate* original_delegate_;
-
-  DISALLOW_COPY_AND_ASSIGN(DragWindowLayerDelegate);
-};
-
-}  // namespace
-
-// This keeps tack of the drag window's state. It creates/destory/updates bounds
-// and opacity based on the current bounds.
+// This keeps track of the drag window's state. It creates/destroys/updates
+// bounds and opacity based on the current bounds.
 class DragWindowController::DragWindowDetails
     : public aura::WindowDelegate,
       public ::wm::LayerDelegateFactory {
@@ -186,8 +136,8 @@ class DragWindowController::DragWindowDetails
   ui::LayerDelegate* CreateDelegate(ui::LayerDelegate* delegate) override {
     if (!delegate)
       return nullptr;
-    DragWindowLayerDelegate* new_delegate =
-        new DragWindowLayerDelegate(original_window_, delegate);
+    wm::ForwardingLayerDelegate* new_delegate = new wm::ForwardingLayerDelegate(
+        WmWindowAura::Get(original_window_), delegate);
     delegates_.push_back(base::WrapUnique(new_delegate));
     return new_delegate;
   }
@@ -227,7 +177,7 @@ class DragWindowController::DragWindowDetails
 
   aura::Window* original_window_ = nullptr;
 
-  std::vector<std::unique_ptr<DragWindowLayerDelegate>> delegates_;
+  std::vector<std::unique_ptr<wm::ForwardingLayerDelegate>> delegates_;
 
   // The copy of window_->layer() and its descendants.
   std::unique_ptr<ui::LayerTreeOwner> layer_owner_;

ash/wm/window_cycle_list.h

@@ -13,9 +13,15 @@
 #include "ash/wm/window_cycle_controller.h"
 #include "base/macros.h"
 
+namespace views {
+class Label;
+class Widget;
+}
+
 namespace ash {
 
 class ScopedShowWindow;
+class WindowCycleView;
 
 // Tracks a set of Windows that can be stepped through. This class is used by
 // the WindowCycleController.
@@ -37,12 +43,15 @@ class ASH_EXPORT WindowCycleList : public WmWindowObserver {
   friend class WindowCycleControllerTest;
   const WindowList& windows() const { return windows_; }
 
-  // aura::WindowObserver overrides:
+  // WmWindowObserver overrides:
   // There is a chance a window is destroyed, for example by JS code. We need to
   // take care of that even if it is not intended for the user to close a window
   // while window cycling.
   void OnWindowDestroying(WmWindow* window) override;
 
+  // Returns true if the window list overlay should be shown.
+  bool ShouldShowUi();
+
   // List of weak pointers to windows to use while cycling with the keyboard.
   // List is built when the user initiates the gesture (i.e. hits alt-tab the
   // first time) and is emptied when the gesture is complete (i.e. releases the
@@ -56,6 +65,13 @@ class ASH_EXPORT WindowCycleList : public WmWindowObserver {
   // Wrapper for the window brought to the front.
   std::unique_ptr<ScopedShowWindow> showing_window_;
 
+  // The top level View for the window cycle UI. May be null if the UI is not
+  // showing.
+  WindowCycleView* cycle_view_;
+
+  // The widget that hosts the window cycle UI.
+  std::unique_ptr<views::Widget> cycle_ui_widget_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowCycleList);
 };