Makes sure bounds and visibilty are updated correctly for new displays

ui/aura/test/aura_test_base.cc

 // Copyright (c) 2012 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 "ui/aura/test/aura_test_base.h"
 
 #include "ui/aura/client/window_parenting_client.h"
 #include "ui/aura/mus/property_utils.h"
 #include "ui/aura/mus/window_tree_client.h"
 #include "ui/aura/mus/window_tree_host_mus.h"
@@ skipping 74 matching lines @@
   helper_->SetUp(context_factory);
 }
 
 void AuraTestBase::TearDown() {
   teardown_called_ = true;
 
   // Flush the message loop because we have pending release tasks
   // and these tasks if un-executed would upset Valgrind.
   RunAllPendingInMessageLoop();
 
+  window_tree_hosts_.clear();
+
   helper_->TearDown();
   ui::TerminateContextFactoryForTests();
   ui::ShutdownInputMethodForTesting();
   testing::Test::TearDown();
 }
 
 Window* AuraTestBase::CreateNormalWindow(int id, Window* parent,
                                          WindowDelegate* delegate) {
   Window* window = new Window(
       delegate ? delegate :
@@ skipping 72 matching lines @@
 void AuraTestBase::OnWmClientJankinessChanged(
     const std::set<Window*>& client_windows,
     bool janky) {}
 
 void AuraTestBase::OnWmWillCreateDisplay(const display::Display& display) {}
 
 void AuraTestBase::OnWmNewDisplay(
     std::unique_ptr<WindowTreeHostMus> window_tree_host,
     const display::Display& display) {
   // Take ownership of the WindowTreeHost.
-  window_tree_host_mus_ = std::move(window_tree_host);
+  window_tree_hosts_.push_back(std::move(window_tree_host));
 }
 
 void AuraTestBase::OnWmDisplayRemoved(WindowTreeHostMus* window_tree_host) {
-  if (window_tree_host_mus_.get() == window_tree_host)
-    window_tree_host_mus_.reset();
+  for (auto iter = window_tree_hosts_.begin(); iter != window_tree_hosts_.end();
+       ++iter) {
+    if (iter->get() == window_tree_host) {
+      window_tree_hosts_.erase(iter);
+      return;
+    }
+  }
+  NOTREACHED();
 }
 
 void AuraTestBase::OnWmDisplayModified(const display::Display& display) {}
 
 ui::mojom::EventResult AuraTestBase::OnAccelerator(uint32_t id,
                                                    const ui::Event& event) {
   return ui::mojom::EventResult::HANDLED;
 }
 
 void AuraTestBase::OnWmPerformMoveLoop(
@@ skipping 25 matching lines @@
 
 void AuraTestBaseWithType::SetUp() {
   DCHECK(!setup_called_);
   setup_called_ = true;
   ConfigureBackend(GetParam());
   AuraTestBase::SetUp();
 }
 
 }  // namespace test
 }  // namespace aura