[Remoting Host] Handle text event characters that are not presented on the keyboard

remoting/host/linux/x11_key_mapper.h

+// 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.
+
+#ifndef REMOTING_HOST_LINUX_X11_KEY_MAPPER_H_
+#define REMOTING_HOST_LINUX_X11_KEY_MAPPER_H_
+
+#include <stdint.h>
+
+#include <memory>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/time/time.h"
+
+namespace base {
+class TickClock;
+}  // namespace base
+
+namespace remoting {
+
+class X11Keyboard;
+
+// This is a helper class for finding keycode for a character and assigning
+// unused keycode to the character when it is not mapped.
+// When the key mapper is destructed, all keycodes changed by the mapper will be
+// reset to map NoSymbol.
+// The key mapper must be used on single thread thread.
+class X11KeyMapper {
+ public:
+  struct MapResult {
+    bool success;
+
+    uint32_t keycode;
+    uint32_t modifiers;
+
+    // If success == false and |retry_after| is not zero, user may retry
+    // AddNewCharacter() after |retry_after| has elapsed.
+    base::TimeDelta retry_after;
+  };
+
+  explicit X11KeyMapper(X11Keyboard* keyboard);
+  ~X11KeyMapper();
+
+  // |code_point|: The Unicode code point for the character.
+  // If the returned result indicates success, caller can use the returned
+  // keycode and modifiers to simulate a key press that can generate the
+  // character.
+  //
+  // Note that the returned result will expire after some amount of time so do
+  // not store the result for later use.
+  MapResult MapCharacter(uint32_t code_point);
+
+  void SetClockForTesting(std::unique_ptr<base::TickClock> clock);
+
+ private:
+  struct KeyInfo;
+
+  // Resets the expiration time of the KeyInfo in available_keycodes_[index]
+  // to now + the expire duration constant.
+  void ResetKeyInfoExpirationTime(std::vector<KeyInfo>::iterator position);
+
+  X11Keyboard* keyboard_;
+  std::unique_ptr<base::TickClock> clock_;
+
+  // Sorted by ascending expiration time.
+  std::vector<KeyInfo> available_keycodes_;
+
+  DISALLOW_COPY_AND_ASSIGN(X11KeyMapper);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_LINUX_X11_KEY_MAPPER_H_