Add DCHECK to detect when a RPH is reused with a different context.

content/browser/renderer_host/render_process_host_impl.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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 2113 matching lines @@
     // later.
     VLOG(1) << "Blocked URL " << url->spec();
     *url = GURL(url::kAboutBlankURL);
   }
 }
 
 // static
 bool RenderProcessHostImpl::IsSuitableHost(RenderProcessHost* host,
                                            BrowserContext* browser_context,
                                            const GURL& site_url) {
-  if (run_renderer_in_process())
+  if (run_renderer_in_process()) {
+    DCHECK_EQ(host->GetBrowserContext(), browser_context)
+        << " Single-process mode does not support multiple browser contexts.";
     return true;
+  }
 
   if (host->GetBrowserContext() != browser_context)
     return false;
 
   // Do not allow sharing of guest hosts. This is to prevent bugs where guest
   // and non-guest storage gets mixed. In the future, we might consider enabling
   // the sharing of guests, in this case this check should be removed and
   // InSameStoragePartition should handle the possible sharing.
   if (host->IsForGuestsOnly())
     return false;
@@ skipping 633 matching lines @@
 
     // Skip widgets in other processes.
     if (rvh->GetProcess()->GetID() != GetID())
       continue;
 
     rvh->OnWebkitPreferencesChanged();
   }
 }
 
 }  // namespace content