Add APIs to the client plugin to re-map and trap key events.

remoting/client/key_event_mapper.h

Index: remoting/client/key_event_mapper.h
diff --git a/remoting/client/key_event_mapper.h b/remoting/client/key_event_mapper.h
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index 0000000000000000000000000000000000000000..c48e089e04aad9887fc12d567633846d3658e485
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+++ b/remoting/client/key_event_mapper.h
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+// Copyright (c) 2012 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_CLIENT_KEY_EVENT_MAPPER_H_
+#define REMOTING_CLIENT_KEY_EVENT_MAPPER_H_
+
+#include <map>
+#include <set>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "remoting/protocol/input_filter.h"
+
+namespace remoting {
+
+// Filtering InputStub which can be used to re-map the USB keycodes of events
+// before they are passed on to the next InputStub in the chain, or to trap
+// events with specific USB keycodes for special handling.
+class KeyEventMapper : public protocol::InputFilter {
+ public:
+  KeyEventMapper();
+  explicit KeyEventMapper(InputStub* input_stub);
+  virtual ~KeyEventMapper();
+
+  // Callback type for use with SetTrapCallback(), below.
+  typedef base::Callback<void(uint32, bool)> KeyTrapCallback;
+
+  // Sets the callback to which trapped keys will be delivered.
+  void SetTrapCallback(KeyTrapCallback callback);
+
+  // Causes events matching |usb_keycode| to be delivered to the trap callback.
+  // Trapped events are not dispatched to the next InputStub in the chain.
+  void TrapKey(uint32 usb_keycode, bool trap_key);
+
+  // Causes events matching |in_usb_keycode| to be mapped to |out_usb_keycode|.
+  // Keys are remapped at most once. Traps are processed before remapping.
+  void RemapKey(uint32 in_usb_keycode, uint32 out_usb_keycode);
+
+  // InputFilter overrides.
+  virtual void InjectKeyEvent(const protocol::KeyEvent& event) OVERRIDE;
+
+ private:
+  std::map<uint32,uint32> mapped_keys;
+  std::set<uint32> trapped_keys;
+  KeyTrapCallback trap_callback;
+
+  DISALLOW_COPY_AND_ASSIGN(KeyEventMapper);
+};
+
+} // namespace remoting
+
+#endif // REMOTING_CLIENT_KEY_EVENT_MAPPER_H_