Why this CL triggers an OilPan crash.

content/browser/browsing_instance.h

Index: content/browser/browsing_instance.h
diff --git a/content/browser/browsing_instance.h b/content/browser/browsing_instance.h
index 34c1f073bbd852c260aecf8eade45656d6d10005..cba1b61e06fd74aa273031c5755baff8aebfc381 100644
--- a/content/browser/browsing_instance.h
+++ b/content/browser/browsing_instance.h
@@ -52,7 +52,7 @@ class SiteInstanceImpl;
 // 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
@@ -72,6 +72,9 @@ class CONTENT_EXPORT BrowsingInstance final
   // 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);
@@ -125,6 +128,9 @@ class CONTENT_EXPORT BrowsingInstance final
   // 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);