Added check in OnChannelError to see if metro/ash desktop is created.

chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.cc

 // Copyright 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 "chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.h"
 
 #include "ash/display/display_info.h"
 #include "ash/display/display_manager.h"
 #include "ash/host/ash_remote_window_tree_host_win.h"
 #include "ash/shell.h"
@@ skipping 69 matching lines @@
 
 void ChromeMetroViewerProcessHost::OnChannelError() {
   // TODO(cpu): At some point we only close the browser. Right now this
   // is very convenient for developing.
   DVLOG(1) << "viewer channel error : Quitting browser";
 
   // Unset environment variable to let breakpad know that metro process wasn't
   // connected.
   ::SetEnvironmentVariableA(env_vars::kMetroConnected, NULL);
 
-  aura::RemoteWindowTreeHostWin::Instance()->Disconnected();
+  // It seems possible that channel is connected, but ASH desktop is not yet
+  // created (instance is still NULL) and we receive channel error.
+  if (aura::RemoteWindowTreeHostWin::Instance()) {
+    aura::RemoteWindowTreeHostWin::Instance()->Disconnected();
+
+    chrome::DecrementKeepAliveCount();
+
+    // If browser is trying to quit, we shouldn't reenter the process.
+    // TODO(shrikant): In general there seem to be issues with how AttemptExit
+    // reentry works. In future release please clean up related code.
+    if (!browser_shutdown::IsTryingToQuit()) {
+      CloseOpenAshBrowsers();
+      chrome::CloseAsh();
+    }
+    // Tell the rest of Chrome about it.
+    content::NotificationService::current()->Notify(
+        chrome::NOTIFICATION_ASH_SESSION_ENDED,
+        content::NotificationService::AllSources(),
+        content::NotificationService::NoDetails());
+    return;
+  }
+
   chrome::DecrementKeepAliveCount();
 
-  // If browser is trying to quit, we shouldn't reenter the process.
-  // TODO(shrikant): In general there seem to be issues with how AttemptExit
-  // reentry works. In future release please clean up related code.
-  if (!browser_shutdown::IsTryingToQuit()) {
-    CloseOpenAshBrowsers();
-    chrome::CloseAsh();
-  }
-  // Tell the rest of Chrome about it.
-  content::NotificationService::current()->Notify(
-      chrome::NOTIFICATION_ASH_SESSION_ENDED,
-      content::NotificationService::AllSources(),
-      content::NotificationService::NoDetails());
-
   // This will delete the MetroViewerProcessHost object. Don't access member
   // variables/functions after this call.
   g_browser_process->platform_part()->OnMetroViewerProcessTerminated();
 }
 
 void ChromeMetroViewerProcessHost::OnChannelConnected(int32 /*peer_pid*/) {
   DVLOG(1) << "ChromeMetroViewerProcessHost::OnChannelConnected: ";
   // Set environment variable to let breakpad know that metro process was
   // connected.
   ::SetEnvironmentVariableA(env_vars::kMetroConnected, "1");
@@ skipping 45 matching lines @@
 void ChromeMetroViewerProcessHost::OnWindowSizeChanged(uint32 width,
                                                        uint32 height) {
   std::vector<ash::DisplayInfo> info_list;
   info_list.push_back(ash::DisplayInfo::CreateFromSpec(
       base::StringPrintf("%dx%d*%f", width, height, gfx::GetDPIScale())));
   ash::Shell::GetInstance()->display_manager()->OnNativeDisplaysChanged(
       info_list);
   aura::RemoteWindowTreeHostWin::Instance()->HandleWindowSizeChanged(width,
                                                                      height);
 }