Why this CL triggers an OilPan crash.

content/browser/browsing_instance.h

 // 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.
 
 #ifndef CONTENT_BROWSER_BROWSING_INSTANCE_H_
 #define CONTENT_BROWSER_BROWSING_INSTANCE_H_
 
 #include <stddef.h>
 
 #include "base/containers/hash_tables.h"
@@ skipping 34 matching lines @@
 // A BrowsingInstance is live as long as any SiteInstance has a reference to
 // it.  A SiteInstance is live as long as any NavigationEntry or RenderViewHost
 // have references to it.  Because both classes are RefCounted, they do not
 // need to be manually deleted.
 //
 // BrowsingInstance has no public members, as it is designed to be
 // visible only from the SiteInstance class.  To get a new
 // SiteInstance that is part of the same BrowsingInstance, use
 // SiteInstance::GetRelatedSiteInstance.  Because of this,
 // BrowsingInstances and SiteInstances are tested together in
-// site_instance_unittest.cc.
+// site_instance_impl_unittest.cc.
 //
 ///////////////////////////////////////////////////////////////////////////////
 class CONTENT_EXPORT BrowsingInstance final
     : public base::RefCounted<BrowsingInstance> {
  private:
   friend class base::RefCounted<BrowsingInstance>;
   friend class SiteInstanceImpl;
   FRIEND_TEST_ALL_PREFIXES(SiteInstanceTest, OneSiteInstancePerSite);
   FRIEND_TEST_ALL_PREFIXES(SiteInstanceTest,
                            OneSiteInstancePerSiteInBrowserContext);
 
   // Create a new BrowsingInstance.
   explicit BrowsingInstance(BrowserContext* context);
 
   ~BrowsingInstance();
 
   // Get the browser context to which this BrowsingInstance belongs.
   BrowserContext* browser_context() const { return browser_context_; }
 
+  // Get the id of this instance.
+  int browsing_instance_id() const { return browsing_instance_id_; }
+
   // Returns whether this BrowsingInstance has registered a SiteInstance for
   // the site of the given URL.
   bool HasSiteInstance(const GURL& url);
 
   // Get the SiteInstance responsible for rendering the given URL.  Should
   // create a new one if necessary, but should not create more than one
   // SiteInstance per site.
   scoped_refptr<SiteInstanceImpl> GetSiteInstanceForURL(const GURL& url);
 
   // Returns a SiteInstance that should be used for subframes when an oopif is
@@ skipping 33 matching lines @@
   // obtained with SiteInstanceImpl::GetSiteForURL.  Note that this map may not
   // contain every active SiteInstance, because a race exists where two
   // SiteInstances can be assigned to the same site.  This is ok in rare cases.
   // It also does not contain SiteInstances which have not yet been assigned a
   // site, such as about:blank.  See NavigatorImpl::ShouldAssignSiteForURL.
   SiteInstanceMap site_instance_map_;
 
   // Number of WebContentses currently using this BrowsingInstance.
   size_t active_contents_count_;
 
+  // ID of this BrowsingInstance.
+  int browsing_instance_id_;
+
   SiteInstanceImpl* default_subframe_site_instance_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(BrowsingInstance);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BROWSING_INSTANCE_H_