More Blimp browser tests for navigation

blimp/engine/session/tab.cc

 // 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.
 
 #include "blimp/engine/session/tab.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "base/trace_event/trace_event.h"
 #include "blimp/common/create_blimp_message.h"
 #include "blimp/common/proto/blimp_message.pb.h"
@@ skipping 57 matching lines @@
 
   content::NavigationController::LoadURLParams params(url);
   params.transition_type = ui::PageTransitionFromInt(
       ui::PAGE_TRANSITION_TYPED | ui::PAGE_TRANSITION_FROM_ADDRESS_BAR);
   params.override_user_agent = content::NavigationController::UA_OVERRIDE_TRUE;
   web_contents_->GetController().LoadURLWithParams(params);
   web_contents_->Focus();
 }
 
 void Tab::GoBack() {
+  if (!web_contents_->GetController().CanGoBack()) {
+    return;
+  }
   DVLOG(1) << "Back in tab " << tab_id_;
   web_contents_->GetController().GoBack();
 }
 
 void Tab::GoForward() {
+  if (!web_contents_->GetController().CanGoForward()) {
+    return;
+  }
   DVLOG(1) << "Forward in tab " << tab_id_;
   web_contents_->GetController().GoForward();
 }
 
 void Tab::Reload() {
   DVLOG(1) << "Reload in tab " << tab_id_;
   web_contents_->GetController().Reload(true);
 }
 
 void Tab::RenderViewCreated(content::RenderViewHost* render_view_host) {
@@ skipping 48 matching lines @@
   navigation_message->set_type(NavigationMessage::NAVIGATION_STATE_CHANGED);
   navigation_message->mutable_navigation_state_changed()
       ->set_page_load_completed(load_status == PageLoadStatus::LOADED);
 
   navigation_message_sender_->ProcessMessage(std::move(message),
                                              net::CompletionCallback());
 }
 
 }  // namespace engine
 }  // namespace blimp