Add a FakeImeFeatureDelegate to the Linux client.

blimp/client/feature/ime_feature.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 BLIMP_CLIENT_FEATURE_IME_FEATURE_H_
 #define BLIMP_CLIENT_FEATURE_IME_FEATURE_H_
 
 #include <map>
 #include <string>
 
@@ skipping 32 matching lines @@
   ~ImeFeature() override;
 
   // Set the BlimpMessageProcessor that will be used to send BlimpMessage::IME
   // messages to the engine.
   void set_outgoing_message_processor(
       std::unique_ptr<BlimpMessageProcessor> processor) {
     outgoing_message_processor_ = std::move(processor);
   }
 
   // Sets a Delegate to be notified of all text input messages.
-  // Passing a null |delegate| causes IME messages to be ignored.
+  // There must be a valid non-null Delegate set before routing messages
+  // to the ImeFeature for processing, until the last message is processed.
   void set_delegate(Delegate* delegate) { delegate_ = delegate; }
 
   // Sends text from IME to the blimp engine.
   void OnImeTextEntered(const std::string& text);
 
- private:
   // BlimpMessageProcessor implementation.
   void ProcessMessage(std::unique_ptr<BlimpMessage> message,
                       const net::CompletionCallback& callback) override;
 
-  // Delegate for processing the text input related messages. |delegate_| must
-  // remain valid until the last message has been passed to ImeFeature.
+ private:
+  // Used to actually show or hide the IME. See notes on |set_delegate|.
   Delegate* delegate_ = nullptr;
 
   // Tab id and render widget id for the input field for which user input is
   // being requested.
   // The values are cached from the ImeMessage::SHOW_IME message and sent back
   // to engine in the subsequent ImeMessage::SET_TEXT message.
   // The cached values are cleared on receiving ImeMessage::HIDE_IME request.
   int tab_id_ = -1;
   int render_widget_id_ = 0;
 
   // Used to send BlimpMessage::IME messages to the engine.
   std::unique_ptr<BlimpMessageProcessor> outgoing_message_processor_;
 
   DISALLOW_COPY_AND_ASSIGN(ImeFeature);
 };
 
 }  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_FEATURE_IME_FEATURE_H_