Added network components for blimp text input feature

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>
+
+#include "base/macros.h"
+#include "blimp/client/blimp_client_export.h"
+#include "blimp/net/blimp_message_processor.h"
+#include "ui/base/ime/text_input_type.h"
+
+namespace blimp {
+namespace client {
+
+// Handles all incoming and outgoing protobuf messages for text input of type
+// BlimpMessage::IME for blimp client.
+// Upon receiving a text input request from the engine, the ImeFeature caches
+// the |tab_id_| and |render_widget_id_| for the request and
+// delegates the request to ImeFeatureDelegate which then opens up the IME.
+// After user is done typing, the text is passed back to ImeFeature, which then
+// sends the text to the engine over network along with the same |tab_id_| and
+// |render_widget_id_|.
+// Any time user taps on an input text, ImeMessage::SHOW_IME message will be
+// sent to client. Similarly, any time the text input is out of focus (e.g. if
+// user navigates away from the currently page or the page loads for the first
+// time), ImeMessage::HIDE_IME will be sent.
+
+class BLIMP_CLIENT_EXPORT ImeFeature : public BlimpMessageProcessor {
+ public:
+  // A delegate to be notified of text input requests.
+  class ImeFeatureDelegate {

[Wez, 2016/03/22 21:43:38]

nit: Either call this ImeFeatureDelegate and move it outside ImeFeature (since
it already has a nicely unique name), or name it simply Delegate and leave it
here.

Having it declared outside ImeFeature would be better if there is any code that
needs to pass around ImeFeatureDelegate pointers without knowing the details of
the class, but I doubt we have those.

[shaktisahu, 2016/03/22 23:45:42]

I think we can't just call it Delegate since it would be implemented by
WebInputBox. Moving it to a separate file is a good idea, but I am  holding on
to it unless required. Also this is in line with other feature delegates such as
NavigationFeatureDelegate etc.

[Wez, 2016/03/23 00:10:53]

I don't understand why the name would make any difference there - it's already
prefixed with ImeFeature::
I'm not suggesting moving it to a different file, just moving it to be
blimp::client::ImeFeatureDelegate - it would be declared immediately before
ImeFeature in that case.  (We don't have a one-class-per-header requirement).
Those should be cleaned up - there's no need for the Foo prefix on FooDelegate
if it's already declared inside class Foo - it can just be Foo::Delegate.

+   public:
+    virtual void OnShowImeRequested(ui::TextInputType input_type,
+                                    const std::string& text) = 0;
+    virtual void OnHideImeRequested() = 0;
+  };
+
+  ImeFeature();
+  ~ImeFeature() override;
+
+  // Set the BlimpMessageProcessor that will be used to send BlimpMessage::IME
+  // messages to the engine.
+  void set_outgoing_message_processor(
+      scoped_ptr<BlimpMessageProcessor> processor) {
+    outgoing_message_processor_ = std::move(processor);
+  }
+
+  // Sets a ImeFeatureDelegate to be notified of all text input messages.
+  void set_delegate(ImeFeatureDelegate* delegate) { delegate_ = delegate; }
+
+  // Sends text from IME to the blimp engine.
+  void OnImeTextEntered(const std::string& text);
+
+ private:
+  // BlimpMessageProcessor implementation.
+  void ProcessMessage(scoped_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.
+  ImeFeatureDelegate* delegate_;
+
+  // 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_;
+  int render_widget_id_;
+
+  // Used to send BlimpMessage::IME messages to the engine.
+  scoped_ptr<BlimpMessageProcessor> outgoing_message_processor_;
+
+  DISALLOW_COPY_AND_ASSIGN(ImeFeature);
+};
+
+}  // namespace client
+}  // namespace blimp
+
+#endif  // BLIMP_CLIENT_FEATURE_IME_FEATURE_H_