Disable pinch-to-zoom gesture on virtual keyboard

ui/keyboard/keyboard_event_filter.h

+// Copyright 2017 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 UI_KEYBOARD_KEYBOARD_EVENT_FILTER_H_
+#define UI_KEYBOARD_KEYBOARD_EVENT_FILTER_H_
+
+#include "base/macros.h"
+#include "ui/events/event_handler.h"
+#include "ui/keyboard/keyboard_export.h"
+
+namespace keyboard {
+
+// EventFilter for the keyboard window, which intercepts events before they are
+// processed by the keyboard window.
+class KEYBOARD_EXPORT KeyboardEventFilter : public ui::EventHandler {
+ public:
+  KeyboardEventFilter() = default;
+  ~KeyboardEventFilter() override = default;
+
+  // ui::EventHandler overrides:
+  void OnGestureEvent(ui::GestureEvent* event) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(KeyboardEventFilter);
+};
+
+}  // namespace keyboard
+
+#endif  // UI_KEYBOARD_KEYBOARD_EVENT_FILTER_H_