Fix an Aura crash several minutes into V2Mirroring

chromecast/browser/cast_content_window.cc

 // Copyright 2014 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 "chromecast/browser/cast_content_window.h"
 
 #include "base/threading/thread_restrictions.h"
 #include "content/public/browser/web_contents.h"
 #include "ipc/ipc_message.h"
 
@@ skipping 36 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(CastFillLayout);
 };
 #endif
 
 CastContentWindow::CastContentWindow() {}
 
 CastContentWindow::~CastContentWindow() {
 #if defined(USE_AURA)
   window_tree_host_.reset();
-  gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, NULL);
+  // We don't delete the screen here to avoid a CHECK failure when
+  // the screen size is queried periodically for metric gathering. b/18101124
 #endif
 }
 
 scoped_ptr<content::WebContents> CastContentWindow::Create(
     const gfx::Size& initial_size,
     content::BrowserContext* browser_context) {
 #if defined(USE_AURA)
   // Aura initialization
-  // TODO(lcwu): We only need a minimal implementation of gfx::screen
+  // TODO(lcwu): We only need a minimal implementation of gfx::Screen
   // and aura's TestScreen will do for us now. We should change to use
   // ozone's screen implementation when it is ready.
-  aura::TestScreen* screen = aura::TestScreen::Create(initial_size);
-  gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, screen);
+  gfx::Screen* old_screen =
+      gfx::Screen::GetScreenByType(gfx::SCREEN_TYPE_NATIVE);
+  if (!old_screen || old_screen->GetPrimaryDisplay().size() != initial_size) {
+    gfx::Screen* new_screen = aura::TestScreen::Create(initial_size);
+    DCHECK(new_screen) << "New screen not created.";
+    gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, new_screen);
+    if (old_screen) {
+      delete old_screen;
+    }
+  }
   CHECK(aura::Env::GetInstance());
   window_tree_host_.reset(
       aura::WindowTreeHost::Create(gfx::Rect(initial_size)));
   window_tree_host_->InitHost();
   window_tree_host_->window()->SetLayoutManager(
       new CastFillLayout(window_tree_host_->window()));
   window_tree_host_->Show();
 #endif
 
   content::WebContents::CreateParams create_params(browser_context, NULL);
   create_params.routing_id = MSG_ROUTING_NONE;
   create_params.initial_size = initial_size;
   content::WebContents* web_contents = content::WebContents::Create(
       create_params);
 
 #if defined(USE_AURA)
   // Add and show content's view/window
   aura::Window* content_window = web_contents->GetNativeView();
   aura::Window* parent = window_tree_host_->window();
   if (!parent->Contains(content_window)) {
     parent->AddChild(content_window);
   }
   content_window->Show();
 #endif
 
   return make_scoped_ptr(web_contents);
 }
 
 }  // namespace chromecast