Clean up RenderViewHostManager swapping logic.

content/browser/web_contents/render_view_host_manager.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_WEB_CONTENTS_RENDER_VIEW_HOST_MANAGER_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_RENDER_VIEW_HOST_MANAGER_H_
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 214 matching lines @@
 
  private:
   friend class RenderViewHostManagerTest;
   friend class TestWebContents;
 
   // Returns whether this tab should transition to a new renderer for
   // cross-site URLs.  Enabled unless we see the --process-per-tab command line
   // switch.  Can be overridden in unit tests.
   bool ShouldTransitionCrossSite();
 
-  // Returns true if the two navigation entries are incompatible in some way
-  // other than site instances. Cases where this can happen include Web UI
-  // to regular web pages. It will cause us to swap RenderViewHosts (and hence
-  // RenderProcessHosts) even if the site instance would otherwise be the same.
-  // As part of this, we'll also force new SiteInstances and BrowsingInstances.
+  // Returns true if for the navigation from |current_entry| to |new_entry|,
+  // a new SiteInstance and BrowsingInstance should be created (even if we are
+  // in a process model that doesn't usually swap).  This forces a process swap
+  // and severs script connections with existing tabs.  Cases where this can
+  // happen include transitions between WebUI and regular web pages.
   // Either of the entries may be NULL.
-  bool ShouldSwapProcessesForNavigation(
-      const NavigationEntry* curr_entry,
+  bool ShouldSwapBrowsingInstanceForNavigation(
+      const NavigationEntry* current_entry,
       const NavigationEntryImpl* new_entry) const;
 
+  // Returns true if it is safe to reuse the current WebUI when navigating from
+  // |curr_entry| to |new_entry|.
   bool ShouldReuseWebUI(
       const NavigationEntry* curr_entry,
       const NavigationEntryImpl* new_entry) const;
 
   // Returns an appropriate SiteInstance object for the given NavigationEntry,
-  // possibly reusing the current SiteInstance.
-  // Never called if --process-per-tab is used.
+  // possibly reusing the current SiteInstance.  If --process-per-tab is used,
+  // this is only called when ShouldSwapBrowsingInstancesForNavigation returns
+  // true.
   SiteInstance* GetSiteInstanceForEntry(
       const NavigationEntryImpl& entry,
-      SiteInstance* curr_instance);
+      SiteInstance* curr_instance,
+      bool force_swap);
 
   // Sets up the necessary state for a new RenderViewHost with the given opener.
   bool InitRenderView(RenderViewHost* render_view_host, int opener_route_id);
 
   // Sets the pending RenderViewHost/WebUI to be the active one. Note that this
   // doesn't require the pending render_view_host_ pointer to be non-NULL, since
   // there could be Web UI switching as well. Call this for every commit.
   void CommitPending();
 
   // Helper method to terminate the pending RenderViewHost.
@@ skipping 50 matching lines @@
 
   // The intersitial page currently shown if any, not own by this class
   // (the InterstitialPage is self-owned, it deletes itself when hidden).
   InterstitialPageImpl* interstitial_page_;
 
   NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderViewHostManager);
 };
 
-}  // namespace content      
+}  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_RENDER_VIEW_HOST_MANAGER_H_