Refactors maximize mode event handling into its own class

ash/common/wm/maximize_mode/maximize_mode_event_handler.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/maximize_mode/maximize_mode_event_handler.h"
+
+#include "ash/common/session/session_state_delegate.h"
+#include "ash/common/wm/window_state.h"
+#include "ash/common/wm/wm_event.h"
+#include "ash/common/wm_shell.h"
+#include "ash/common/wm_window.h"
+#include "ui/events/event.h"
+
+namespace ash {
+namespace wm {
+namespace {
+
+// The height of the area in which a touch operation leads to exiting the
+// full screen mode.
+const int kLeaveFullScreenAreaHeightInPixel = 2;

[James Cook, 2016/06/28 23:10:21]

Aside: This seems like a weird feature. A 2-pixel tap target is awfully small.
Strange.

+
+}  // namespace
+
+MaximizeModeEventHandler::MaximizeModeEventHandler() {}
+
+MaximizeModeEventHandler::~MaximizeModeEventHandler() {}
+
+bool MaximizeModeEventHandler::ToggleFullscreen(const ui::TouchEvent& event) {
+  if (event.type() != ui::ET_TOUCH_PRESSED)
+    return false;
+
+  const SessionStateDelegate* delegate =
+      WmShell::Get()->GetSessionStateDelegate();
+
+  if (delegate->IsScreenLocked() ||
+      delegate->GetSessionState() !=
+          SessionStateDelegate::SESSION_STATE_ACTIVE) {
+    return false;
+  }
+
+  // Find the active window (from the primary screen) to un-fullscreen.
+  WmWindow* window = WmShell::Get()->GetActiveWindow();
+  if (!window)
+    return false;
+
+  WindowState* window_state = window->GetWindowState();
+  if (!window_state->IsFullscreen() || window_state->in_immersive_fullscreen())
+    return false;
+
+  // Test that the touch happened in the top or bottom lines.
+  int y = event.y();
+  if (y >= kLeaveFullScreenAreaHeightInPixel &&
+      y < (window->GetBounds().height() - kLeaveFullScreenAreaHeightInPixel)) {
+    return false;
+  }
+
+  WMEvent toggle_fullscreen(WM_EVENT_TOGGLE_FULLSCREEN);
+  window->GetWindowState()->OnWMEvent(&toggle_fullscreen);
+  return true;
+}
+
+}  // namespace wm
+}  // namespace ash