Restrict number of BlimpContents to [0, 1]

blimp/client/core/contents/blimp_contents_manager.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/client/core/contents/blimp_contents_manager.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "blimp/client/core/contents/tab_control_feature.h"
@@ skipping 38 matching lines @@
     NavigationFeature* nav_feature,
     TabControlFeature* tab_control_feature)
     : ime_feature_(ime_feature),
       navigation_feature_(nav_feature),
       tab_control_feature_(tab_control_feature),
       weak_ptr_factory_(this) {}
 
 BlimpContentsManager::~BlimpContentsManager() {}
 
 std::unique_ptr<BlimpContentsImpl> BlimpContentsManager::CreateBlimpContents() {
+  if (tab_exists_) return nullptr;
+  tab_exists_ = true;
+
   int id = CreateBlimpContentsId();
 
   std::unique_ptr<BlimpContentsImpl> new_contents =
       base::MakeUnique<BlimpContentsImpl>(id, ime_feature_, navigation_feature_,
                                           tab_control_feature_);
 
   // Create an observer entry for the contents.
   std::unique_ptr<BlimpContentsDeletionObserver> observer =
       base::MakeUnique<BlimpContentsDeletionObserver>(this, new_contents.get());
   observer_map_.insert(
@@ skipping 24 matching lines @@
   // dummy tab id. Need to return real case id when Blimp supports multiple
   // tabs.
   return kDummyTabId;
 }
 
 void BlimpContentsManager::EraseObserverFromMap(int id) {
   observer_map_.erase(id);
 }
 
 void BlimpContentsManager::OnContentsDestroyed(BlimpContents* contents) {
+  DCHECK(tab_exists_);
+  tab_exists_ = false;
+
   int id = static_cast<BlimpContentsImpl*>(contents)->id();
 
   // Notify the engine that we've destroyed the BlimpContents.
   tab_control_feature_->CloseTab(id);
 
   // Destroy the observer entry from the observer_map_.
   DCHECK(base::ThreadTaskRunnerHandle::Get());
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&BlimpContentsManager::EraseObserverFromMap,
                             this->GetWeakPtr(), id));
 }
 
 base::WeakPtr<BlimpContentsManager> BlimpContentsManager::GetWeakPtr() {
   return weak_ptr_factory_.GetWeakPtr();
 }
 
 }  // namespace client
 }  // namespace blimp