Leave fullscreen mode in an app window when ESC key is pressed.

apps/shell_window.cc

 // Copyright 2013 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 "apps/shell_window.h"
 
 #include "apps/shell_window_geometry_cache.h"
 #include "apps/shell_window_registry.h"
 #include "apps/ui/native_app_window.h"
 #include "base/command_line.h"
@@ skipping 265 matching lines @@
                                  WindowOpenDisposition disposition,
                                  const gfx::Rect& initial_pos,
                                  bool user_gesture,
                                  bool* was_blocked) {
   DCHECK(Profile::FromBrowserContext(new_contents->GetBrowserContext()) ==
       profile_);
   delegate_->AddNewContents(profile_, new_contents, disposition,
                             initial_pos, user_gesture, was_blocked);
 }
 
+bool ShellWindow::PreHandleKeyboardEvent(
+    content::WebContents* source,
+    const content::NativeWebKeyboardEvent& event,
+    bool* is_keyboard_shortcut) {
+  // Here, we can handle a key event before the content gets it. When we are
+  // fullscreen, we want to allow the user to leave when ESC is pressed.
+  // However, if the application has the "overrideEscFullscreen" permission, we
+  // should let it override that behavior.
+  // ::HandleKeyboardEvent() will only be called if the KeyEvent's default
+  // action is not prevented.
+  // Thus, we should handle the KeyEvent here only if the permission is not set.
+  if (event.windowsKeyCode == ui::VKEY_ESCAPE &&
+      (fullscreen_for_tab_ || fullscreen_for_window_api_) &&
+      !extension_->HasAPIPermission(APIPermission::kOverrideEscFullscreen)) {
+    Restore();
+    return true;
+  }
+
+  return false;
+}
+
 void ShellWindow::HandleKeyboardEvent(
     WebContents* source,
     const content::NativeWebKeyboardEvent& event) {
+  // If the window is currently fullscreen, ESC should leave fullscreen.
+  // If this code is being called for ESC, that means that the KeyEvent's
+  // default behavior was not prevented by the content.
+  if (event.windowsKeyCode == ui::VKEY_ESCAPE &&
+      (fullscreen_for_tab_ || fullscreen_for_window_api_)) {
+    Restore();
+    return;
+  }
+
   native_app_window_->HandleKeyboardEvent(event);
 }
 
 void ShellWindow::RequestToLockMouse(WebContents* web_contents,
                                      bool user_gesture,
                                      bool last_unlocked_by_target) {
   bool has_permission = IsExtensionWithPermissionOrSuggestInConsole(
       APIPermission::kPointerLock,
       extension_,
       web_contents->GetRenderViewHost());
@@ skipping 450 matching lines @@
         region.bounds.x(),
         region.bounds.y(),
         region.bounds.right(),
         region.bounds.bottom(),
         region.draggable ? SkRegion::kUnion_Op : SkRegion::kDifference_Op);
   }
   return sk_region;
 }
 
 }  // namespace apps