Implement "pinned" mode in ash.

ash/wm/screen_pinning_controller.cc

Index: ash/wm/screen_pinning_controller.cc
diff --git a/ash/wm/screen_pinning_controller.cc b/ash/wm/screen_pinning_controller.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f312288ec55f36e68ed1443ed6d34799f1388a9f
--- /dev/null
+++ b/ash/wm/screen_pinning_controller.cc
@@ -0,0 +1,403 @@
+// 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/wm/screen_pinning_controller.h"
+
+#include <algorithm>
+#include <vector>
+
+#include "ash/aura/wm_window_aura.h"
+#include "ash/common/shell_window_ids.h"
+#include "ash/common/wm/window_state.h"
+#include "ash/common/wm_shell_common.h"
+#include "ash/common/wm_window.h"
+#include "ash/common/wm_window_observer.h"
+#include "ash/display/window_tree_host_manager.h"
+#include "ash/shell.h"
+#include "ash/wm/dim_window.h"
+#include "base/auto_reset.h"
+#include "base/logging.h"
+#include "base/stl_util.h"
+#include "ui/aura/window_observer.h"
+
+namespace ash {
+namespace {
+
+WmWindow* CreateDimWindow(WmWindow* container) {
+  DimWindow* dim_window = new DimWindow(WmWindowAura::GetAuraWindow(container));
+  dim_window->SetDimOpacity(1);  // Set whole black.
+  WmWindow* result = WmWindowAura::Get(dim_window);
+  result->SetFullscreen();
+  result->Show();
+  return result;
+}
+
+// Returns a list of WmWindows corresponding to SystemModalContainers,
+// except ones whose root is shared with |pinned_window|.
+std::vector<WmWindow*> GetSystemModalWindowsExceptPinned(
+    WmWindow* pinned_window) {
+  WmWindow* pinned_root = pinned_window->GetRootWindow();
+
+  std::vector<WmWindow*> result;
+  for (WmWindow* system_modal : WmWindowAura::FromAuraWindows(
+           ash::Shell::GetContainersFromAllRootWindows(
+               kShellWindowId_SystemModalContainer, nullptr))) {
+    if (system_modal->GetRootWindow() == pinned_root)
+      continue;
+    result.push_back(system_modal);
+  }
+  return result;
+}
+
+void AddObserverToChildren(WmWindow* container,
+                           aura::WindowObserver* observer) {
+  for (WmWindow* child : container->GetChildren()) {
+    WmWindowAura::GetAuraWindow(child)->AddObserver(observer);
+  }
+}
+
+void RemoveObserverFromChildren(WmWindow* container,
+                                aura::WindowObserver* observer) {
+  for (WmWindow* child : container->GetChildren()) {
+    WmWindowAura::GetAuraWindow(child)->RemoveObserver(observer);
+  }
+}
+
+}  // namespace
+
+// Adapter to fire OnPinnedContainerWindowStackingChanged().
+class ScreenPinningController::PinnedContainerChildWindowObserver
+    : public aura::WindowObserver {
+ public:
+  explicit PinnedContainerChildWindowObserver(
+      ScreenPinningController* controller)
+      : controller_(controller) {}
+
+  void OnWindowStackingChanged(aura::Window* window) override {
+    controller_->OnPinnedContainerWindowStackingChanged(
+        WmWindowAura::Get(window));
+  }
+
+ private:
+  ScreenPinningController* controller_;
+  DISALLOW_COPY_AND_ASSIGN(PinnedContainerChildWindowObserver);
+};
+
+// Adapter to translate OnWindowAdded/OnWillRemoveWindow for the container
+// containing the pinned window, to the corresponding controller's methods.
+class ScreenPinningController::PinnedContainerWindowObserver
+    : public aura::WindowObserver {
+ public:
+  explicit PinnedContainerWindowObserver(ScreenPinningController* controller)
+      : controller_(controller) {}
+
+  void OnWindowAdded(aura::Window* new_window) override {
+    controller_->OnWindowAddedToPinnedContainer(WmWindowAura::Get(new_window));
+  }
+  void OnWillRemoveWindow(aura::Window* window) override {
+    controller_->OnWillRemoveWindowFromPinnedContainer(
+        WmWindowAura::Get(window));
+  }
+  void OnWindowDestroying(aura::Window* window) override {
+    // Just in case. There is nothing we can do here.
+    window->RemoveObserver(this);
+  }
+
+ private:
+  ScreenPinningController* controller_;
+  DISALLOW_COPY_AND_ASSIGN(PinnedContainerWindowObserver);
+};
+
+// Adapter to fire OnSystemModalContainerWindowStackingChanged().
+class ScreenPinningController::SystemModalContainerChildWindowObserver
+    : public aura::WindowObserver {
+ public:
+  explicit SystemModalContainerChildWindowObserver(
+      ScreenPinningController* controller)
+      : controller_(controller) {}
+
+  void OnWindowStackingChanged(aura::Window* window) override {
+    controller_->OnSystemModalContainerWindowStackingChanged(
+        WmWindowAura::Get(window));
+  }
+
+ private:
+  ScreenPinningController* controller_;
+  DISALLOW_COPY_AND_ASSIGN(SystemModalContainerChildWindowObserver);
+};
+
+// Adapter to translate OnWindowAdded/OnWillRemoveWindow for the
+// SystemModalContainer to the corresponding controller's methods.
+class ScreenPinningController::SystemModalContainerWindowObserver
+    : public aura::WindowObserver {
+ public:
+  explicit SystemModalContainerWindowObserver(
+      ScreenPinningController* controller)
+      : controller_(controller) {}
+
+  void OnWindowAdded(aura::Window* new_window) override {
+    controller_->OnWindowAddedToSystemModalContainer(
+        WmWindowAura::Get(new_window));
+  }
+  void OnWillRemoveWindow(aura::Window* window) override {
+    controller_->OnWillRemoveWindowFromSystemModalContainer(
+        WmWindowAura::Get(window));
+  }
+  void OnWindowDestroying(aura::Window* window) override {
+    // Just in case. There is nothing we can do here.
+    window->RemoveObserver(this);
+  }
+
+ private:
+  ScreenPinningController* controller_;
+  DISALLOW_COPY_AND_ASSIGN(SystemModalContainerWindowObserver);
+};
+
+// Tracks DimWindow's life.
+class ScreenPinningController::DimWindowObserver : public aura::WindowObserver {
+ public:
+  explicit DimWindowObserver(ScreenPinningController* controller)
+      : controller_(controller) {}
+
+  void OnWindowParentChanged(aura::Window* window,
+                             aura::Window* parent) override {
+    // In case of parent change, there is nothing we can do for that change.
+    // Also, it is unsafe to delete the moving window here, because it could
+    // cause SEGV. Instead, we just hide it.
+    // Note that, the window is still tracked by the ScreenPinningController,
+    // so that it should be deleted on "unpin", at least.
+    window->Hide();
+  }
+
+  void OnWindowDestroying(aura::Window* window) override {
+    controller_->OnDimWindowDestroying(WmWindowAura::Get(window));
+  }
+
+ private:
+  ScreenPinningController* controller_;
+  DISALLOW_COPY_AND_ASSIGN(DimWindowObserver);
+};
+
+ScreenPinningController::ScreenPinningController(
+    WmShellCommon* wm_shell_common,
+    WindowTreeHostManager* window_tree_host_manager)
+    : wm_shell_common_(wm_shell_common),
+      window_tree_host_manager_(window_tree_host_manager),
+      pinned_container_window_observer_(
+          new PinnedContainerWindowObserver(this)),
+      pinned_container_child_window_observer_(
+          new PinnedContainerChildWindowObserver(this)),
+      system_modal_container_window_observer_(
+          new SystemModalContainerWindowObserver(this)),
+      system_modal_container_child_window_observer_(
+          new SystemModalContainerChildWindowObserver(this)),
+      dim_window_observer_(new DimWindowObserver(this)) {
+  wm_shell_common_->AddShellObserver(this);
+  window_tree_host_manager_->AddObserver(this);
+}
+
+ScreenPinningController::~ScreenPinningController() {
+  window_tree_host_manager_->RemoveObserver(this);
+  wm_shell_common_->RemoveShellObserver(this);
+}
+
+bool ScreenPinningController::IsPinned() const {
+  return pinned_window_ != nullptr;
+}
+
+void ScreenPinningController::OnPinnedStateChanged(WmWindow* pinned_window) {
+  if (pinned_window->GetWindowState()->IsPinned()) {
+    if (pinned_window_) {
+      LOG(DFATAL) << "Pinned mode is enabled, while it is already in "
+                  << "the pinned mode";
+      return;
+    }
+
+    WmWindow* container = pinned_window->GetParent();
+    std::vector<WmWindow*> system_modal_containers =
+        GetSystemModalWindowsExceptPinned(pinned_window);
+
+    // Set up the container which has the pinned window.
+    pinned_window_ = pinned_window;
+    background_window_ = CreateDimWindow(container);
+    container->StackChildAtTop(pinned_window);
+    container->StackChildBelow(background_window_, pinned_window);
+
+    // Set the dim windows to the system containers, other than the one which
+    // the root window of the pinned window holds.
+    for (WmWindow* system_modal : system_modal_containers) {
+      WmWindow* dim_window = CreateDimWindow(system_modal);
+      system_modal->StackChildAtBottom(dim_window);
+      dim_windows_.push_back(dim_window);
+      WmWindowAura::GetAuraWindow(dim_window)
+          ->AddObserver(dim_window_observer_.get());
+    }
+
+    // Set observers.
+    WmWindowAura::GetAuraWindow(container)->AddObserver(
+        pinned_container_window_observer_.get());
+    AddObserverToChildren(container,
+                          pinned_container_child_window_observer_.get());
+    for (WmWindow* system_modal : system_modal_containers) {
+      WmWindowAura::GetAuraWindow(system_modal)
+          ->AddObserver(system_modal_container_window_observer_.get());
+      AddObserverToChildren(
+          system_modal, system_modal_container_child_window_observer_.get());
+    }
+  } else {
+    if (pinned_window != pinned_window_) {
+      LOG(DFATAL) << "Pinned mode is being disabled, but for the different "
+                  << "target window.";
+      return;
+    }
+
+    WmWindow* container = pinned_window->GetParent();
+    std::vector<WmWindow*> system_modal_containers =
+        GetSystemModalWindowsExceptPinned(pinned_window_);
+
+    // Unset observers.
+    for (WmWindow* system_modal :
+         GetSystemModalWindowsExceptPinned(pinned_window_)) {
+      RemoveObserverFromChildren(
+          system_modal, system_modal_container_child_window_observer_.get());
+      WmWindowAura::GetAuraWindow(system_modal)
+          ->RemoveObserver(system_modal_container_window_observer_.get());
+    }
+    RemoveObserverFromChildren(container,
+                               pinned_container_child_window_observer_.get());
+    WmWindowAura::GetAuraWindow(container)->RemoveObserver(
+        pinned_container_window_observer_.get());
+
+    // Delete the dim windows. This works, but do not use RAII, because
+    // the window is owned by the parent.
+    // Note: dim_windows_ will be updated during the deletion. So, copy is
+    // needed.
+    for (WmWindow* dim_window : std::vector<WmWindow*>(dim_windows_)) {
+      delete WmWindowAura::GetAuraWindow(dim_window);
+    }
+    DCHECK(dim_windows_.empty());
+    delete WmWindowAura::GetAuraWindow(background_window_);
+    background_window_ = nullptr;
+
+    pinned_window_ = nullptr;
+  }
+}
+
+void ScreenPinningController::OnWindowAddedToPinnedContainer(
+    WmWindow* new_window) {
+  KeepPinnedWindowOnTop();
+  WmWindowAura::GetAuraWindow(new_window)
+      ->AddObserver(pinned_container_child_window_observer_.get());
+}
+
+void ScreenPinningController::OnWillRemoveWindowFromPinnedContainer(
+    WmWindow* window) {
+  WmWindowAura::GetAuraWindow(window)->RemoveObserver(
+      pinned_container_child_window_observer_.get());
+  if (window == pinned_window_) {
+    pinned_window_->GetWindowState()->Restore();
+    return;
+  }
+  if (window == background_window_) {
+    background_window_ = nullptr;
+    return;
+  }
+}
+
+void ScreenPinningController::OnPinnedContainerWindowStackingChanged(
+    WmWindow* window) {
+  KeepPinnedWindowOnTop();
+}
+
+void ScreenPinningController::OnWindowAddedToSystemModalContainer(
+    WmWindow* new_window) {
+  KeepDimWindowAtBottom(new_window->GetParent());
+  WmWindowAura::GetAuraWindow(new_window)
+      ->AddObserver(system_modal_container_child_window_observer_.get());
+}
+
+void ScreenPinningController::OnWillRemoveWindowFromSystemModalContainer(
+    WmWindow* window) {
+  WmWindowAura::GetAuraWindow(window)->RemoveObserver(
+      system_modal_container_child_window_observer_.get());
+}
+
+void ScreenPinningController::OnSystemModalContainerWindowStackingChanged(
+    WmWindow* window) {
+  KeepDimWindowAtBottom(window->GetParent());
+}
+
+void ScreenPinningController::OnDimWindowDestroying(WmWindow* window) {
+  dim_windows_.erase(
+      std::find(dim_windows_.begin(), dim_windows_.end(), window));
+}
+
+void ScreenPinningController::OnDisplayConfigurationChanged() {
+  // Note: this is called on display attached or detached.
+  if (!IsPinned())
+    return;
+
+  // On display detaching, all necessary windows are transfered to the
+  // primary display's tree, and called this.
+  // So, delete the dim windows which are not a part of target system modal
+  // container.
+  // On display attaching, the new system modal container does not have the
+  // dim window. So create it.
+
+  // First, delete unnecessary dim windows.
+  // The delete will update dim_windows_, so create the copy is needed.
+  for (WmWindow* dim_window : std::vector<WmWindow*>(dim_windows_)) {
+    if (!dim_window->GetTargetVisibility())
+      delete WmWindowAura::GetAuraWindow(dim_window);
+  }
+
+  // Then, create missing dim_windows.
+  std::vector<WmWindow*> system_modal_containers =
+      GetSystemModalWindowsExceptPinned(pinned_window_);
+  for (WmWindow* system_modal : system_modal_containers) {
+    const std::vector<WmWindow*> children = system_modal->GetChildren();
+    if (!children.empty() && ContainsValue(dim_windows_, children[0])) {
+      // The system modal dialog has the dim window.
+      continue;
+    }
+
+    // This is the new system modal dialog.
+    WmWindow* dim_window = CreateDimWindow(system_modal);
+    system_modal->StackChildAtBottom(dim_window);
+    dim_windows_.push_back(dim_window);
+    WmWindowAura::GetAuraWindow(dim_window)
+        ->AddObserver(dim_window_observer_.get());
+
+    // Set observers to the tree.
+    WmWindowAura::GetAuraWindow(system_modal)
+        ->AddObserver(system_modal_container_window_observer_.get());
+    AddObserverToChildren(system_modal,
+                          system_modal_container_child_window_observer_.get());
+  }
+}
+
+void ScreenPinningController::KeepPinnedWindowOnTop() {
+  if (in_restacking_)
+    return;
+
+  base::AutoReset<bool> auto_reset(&in_restacking_, true);
+  WmWindow* container = pinned_window_->GetParent();
+  container->StackChildAtTop(pinned_window_);
+  container->StackChildBelow(background_window_, pinned_window_);
+}
+
+void ScreenPinningController::KeepDimWindowAtBottom(WmWindow* container) {
+  if (in_restacking_)
+    return;
+
+  base::AutoReset<bool> auto_reset(&in_restacking_, true);
+  for (WmWindow* dim_window : dim_windows_) {
+    if (dim_window->GetParent() == container) {
+      container->StackChildAtBottom(dim_window);
+      break;
+    }
+  }
+}
+
+}  // namespace ash