"Top Document Isolation" mode

content/browser/site_instance_impl.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_SITE_INSTANCE_IMPL_H_
 #define CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 26 matching lines @@
   int32_t GetId() override;
   bool HasProcess() const override;
   RenderProcessHost* GetProcess() override;
   BrowserContext* GetBrowserContext() const override;
   const GURL& GetSiteURL() const override;
   SiteInstance* GetRelatedSiteInstance(const GURL& url) override;
   bool IsRelatedSiteInstance(const SiteInstance* instance) override;
   size_t GetRelatedActiveContentsCount() override;
   bool RequiresDedicatedProcess() override;
 
+  // Returns the SiteInstance, related to this one, that should be used
+  // for subframes when an oopif is required, but a dedicated process is not.
+  // This SiteInstance will be created if it doesn't already exist. There is
+  // at most one of these per BrowsingInstance.
+  SiteInstance* GetDefaultSubframeSiteInstance();
+
   // Set the web site that this SiteInstance is rendering pages for.
   // This includes the scheme and registered domain, but not the port.  If the
   // URL does not have a valid registered domain, then the full hostname is
   // stored.
   void SetSite(const GURL& url);
   bool HasSite() const;
 
   // Returns whether there is currently a related SiteInstance (registered with
   // BrowsingInstance) for the site of the given url.  If so, we should try to
   // avoid dedicating an unused SiteInstance to it (e.g., in a new tab).
@@ skipping 24 matching lines @@
   // that, unlike active_frame_count, this does not count pending RFHs.
   void IncrementRelatedActiveContentsCount();
 
   // Decrease the number of active WebContentses using this SiteInstance. Note
   // that, unlike active_frame_count, this does not count pending RFHs.
   void DecrementRelatedActiveContentsCount();
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
+  bool is_default_subframe_site_instance() {
+    return is_default_subframe_site_instance_;
+  }
+
   // Sets the global factory used to create new RenderProcessHosts.  It may be
   // NULL, in which case the default RenderProcessHost will be created (this is
   // the behavior if you don't call this function).  The factory must be set
   // back to NULL before it's destroyed; ownership is not transferred.
   static void set_render_process_host_factory(
       const RenderProcessHostFactory* rph_factory);
 
   // Get the effective URL for the given actual URL.  This allows the
   // ContentBrowserClient to override the SiteInstance's site for certain URLs.
   // For example, Chrome uses this to replace hosted app URLs with extension
@@ skipping 17 matching lines @@
   friend class SiteInstance;
 
   // Virtual to allow tests to extend it.
   ~SiteInstanceImpl() override;
 
   // Create a new SiteInstance.  Protected to give access to BrowsingInstance
   // and tests; most callers should use Create or GetRelatedSiteInstance
   // instead.
   explicit SiteInstanceImpl(BrowsingInstance* browsing_instance);
 
+  // Only BrowsingInstance should call this.
+  void set_is_default_subframe_site_instance() {
+    is_default_subframe_site_instance_ = true;
+  }
+
  private:
   // RenderProcessHostObserver implementation.
   void RenderProcessHostDestroyed(RenderProcessHost* host) override;
   void RenderProcessWillExit(RenderProcessHost* host) override;
   void RenderProcessExited(RenderProcessHost* host,
                            base::TerminationStatus status,
                            int exit_code) override;
 
   // Used to restrict a process' origin access rights.
   void LockToOrigin();
 
   // An object used to construct RenderProcessHosts.
   static const RenderProcessHostFactory* g_render_process_host_factory_;
 
   // The next available SiteInstance ID.
   static int32_t next_site_instance_id_;
 
   // A unique ID for this SiteInstance.
   int32_t id_;
 
   // The number of active frames in this SiteInstance.
-  size_t active_frame_count_;
+  size_t active_frame_count_ = 0;

[Charlie Reis, 2016/03/25 19:47:13]

Style question: Is this a new practice that we're moving to in general?  I
haven't seen inline initialization in other code yet, and I kind of like knowing
where to look (i.e., the constructor(s)).  I won't object if this style has
already been discussed, though.

[ncarter (slow), 2016/03/28 22:00:29]

It's been allowed for over a year:
https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/zqB-DySA4V0

(It's also on http://chromium-cpp.appspot.com/ as "non-static Non-Static Class
Member Initializer").

Personally I prefer it if it's used consistently within a class, and it's
particularly beneficial when there is more than one ctor. But I would be happy
to retract this part of the change if you want. It didn't occur to me that it
would be controversial.

[Charlie Reis, 2016/03/29 17:17:12]

Ah, interesting.  Thanks for letting me know.
Let's back it out of this CL, anyway, just to avoid derailing the conversation. 
Maybe we can do it separately, but this seems like one of the cases people
weren't happy with on the discussion list: initializers split between here and
in the constructor, requiring you to look in both places.  (That seems a little
harder to read and harder to verify that all of the members get initialized,
since it's easy to assume that anything missing must be handled in the other
file.)

 
   // BrowsingInstance to which this SiteInstance belongs.
   scoped_refptr<BrowsingInstance> browsing_instance_;
 
   // Current RenderProcessHost that is rendering pages for this SiteInstance.
   // This pointer will only change once the RenderProcessHost is destructed.  It
   // will still remain the same even if the process crashes, since in that
   // scenario the RenderProcessHost remains the same.
-  RenderProcessHost* process_;
+  RenderProcessHost* process_ = nullptr;
 
   // The web site that this SiteInstance is rendering pages for.
   GURL site_;
 
   // Whether SetSite has been called.
-  bool has_site_;
+  bool has_site_ = false;
+  bool is_default_subframe_site_instance_ = false;

[Charlie Reis, 2016/03/25 19:47:13]

nit: Add a blank line before and a comment about this.

[ncarter (slow), 2016/03/28 22:00:29]

Done.

 
   base::ObserverList<Observer, true> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteInstanceImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_