exo: Implement custom fullscreening for ShellSurfaces.

components/exo/shell_surface.cc

Index: components/exo/shell_surface.cc
diff --git a/components/exo/shell_surface.cc b/components/exo/shell_surface.cc
index 9f3aaadd0097b18454bf31baeb7052db47771fae..06c277d2b644693846f47f9f7e80cee1a638d89e 100644
--- a/components/exo/shell_surface.cc
+++ b/components/exo/shell_surface.cc
@@ -8,6 +8,7 @@
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/wm/window_resizer.h"
 #include "ash/common/wm/window_state.h"
+#include "ash/common/wm/window_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/wm/window_state_aura.h"
 #include "ash/wm/window_util.h"
@@ -27,6 +28,7 @@
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/gfx/path.h"
 #include "ui/views/widget/widget.h"
+#include "ui/views/widget/widget_observer.h"
 #include "ui/wm/core/shadow.h"
 #include "ui/wm/core/shadow_controller.h"
 #include "ui/wm/core/shadow_types.h"
@@ -98,6 +100,39 @@ class CustomWindowTargeter : public aura::WindowTargeter {
   DISALLOW_COPY_AND_ASSIGN(CustomWindowTargeter);
 };
 
+// Handles a user's fullscreen request (Shift+F4/F4).
+class CustomWindowStateDelegate : public ash::wm::WindowStateDelegate,
+                                  public views::WidgetObserver {
+ public:
+  explicit CustomWindowStateDelegate(views::Widget* widget) : widget_(widget) {
+    widget_->AddObserver(this);
+  }
+  ~CustomWindowStateDelegate() override {
+    if (widget_)
+      widget_->RemoveObserver(this);
+  }
+
+  // Overridden from ash::wm::WindowStateDelegate:
+  bool ToggleFullscreen(ash::wm::WindowState* window_state) override {
+    if (widget_) {
+      bool enter_fullscreen = !window_state->IsFullscreen();
+      widget_->SetFullscreen(enter_fullscreen);
+    }
+    return true;
+  }
+
+  // Overridden from views::WidgetObserver:
+  void OnWidgetDestroying(views::Widget* widget) override {
+    widget_->RemoveObserver(this);
+    widget_ = nullptr;
+  }
+
+ private:
+  views::Widget* widget_;
+
+  DISALLOW_COPY_AND_ASSIGN(CustomWindowStateDelegate);
+};
+
 class ShellSurfaceWidget : public views::Widget {
  public:
   explicit ShellSurfaceWidget(ShellSurface* shell_surface)
@@ -908,6 +943,10 @@ void ShellSurface::CreateShellSurfaceWidget(ui::WindowShowState show_state) {
         ui::AcceleratorManager::kNormalPriority, this);
   }
 
+  // Set delegate for handling of fullscreening.
+  window_state->SetDelegate(std::unique_ptr<ash::wm::WindowStateDelegate>(
+      new CustomWindowStateDelegate(widget_)));
+
   // Show widget next time Commit() is called.
   pending_show_widget_ = true;
 }