Added network components for blimp text input feature

blimp/common/proto/ime.proto

+// 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.
+//
+// Message definitions for text input messages.
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+
+package blimp;
+
+message ImeMessage {
+  enum Type {
+    UNKNOWN = 0;
+
+    // Server => Client types.
+    SHOW_IME = 1;
+    HIDE_IME = 2;
+    SHOW_TEXT = 3;

[nyquist, 2016/03/10 00:57:13]

SHOW_TEXT seems to be used to send text from the client to the Engine. And if we
receive this on the client, we hit a NOTREACHED.
Should this be under Client => Server below?

[shaktisahu, 2016/03/15 23:44:13]

Done.

+
+    // Client => Server types.
+  }
+
+  optional Type type = 1;
+  optional int32 text_input_type = 2;

[David Trainor- moved to gerrit, 2016/03/14 17:59:42]

This probably shouldn't be an int.  We should roll this up into a proto enum or
something similar.

[shaktisahu, 2016/03/15 23:44:13]

Done.

+  optional string ime_text = 3;
+}