Add a basic UI to the Android Blimp client.

blimp/common/proto/navigation.proto

+// Copyright 2015 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 browser navigation messages.
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+
+package blimp;
+
+message LoadUrlMessage {
+  // The text to generate and create a URL from.  This might be a URL or might

[haibinlu, 2015/11/09 18:58:43]

could you elaborate? maybe give some examples.

[David Trainor- moved to gerrit, 2015/11/09 19:27:17]

I'll put some examples here.  Thanks :).

+  // not.  It might be text that should be turned into a search URL.
+  optional string url = 1;
+}
+
+message NavigationStateChangeMessage {
+  // If the URL changed, this will include the new URL string.
+  optional string url = 1;
+
+  // If the favicon of the page changed, this should include the serialized
+  // bitmap of the favicon.
+  optional bytes favicon = 2;
+
+  // If the title changed, this will contain the new title string.
+  optional string title = 3;
+}
+
+message NavigationMessage {
+  enum Type {
+    // Server => Client types.
+    NAVIGATION_STATE_CHANGED = 1;
+
+    // Client => Server types.
+    LOAD_URL = 2;
+    GO_BACK = 3;

[haibinlu, 2015/11/09 18:58:43]

add FORWARD too?

[David Trainor- moved to gerrit, 2015/11/09 19:27:17]

Good point, although I'm not going to bother adding any UI for that right now
(short of making a pretty UI it'll just clutter the toolbar).

+    RELOAD = 4;
+  }
+
+  optional Type type = 1;
+
+  optional NavigationStateChangeMessage navigation_state_change = 1000;
+  optional LoadUrlMessage load_url = 1001;
+}