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// 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.
#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "content/common/content_export.h"
#include "url/gurl.h"
namespace content {
class BrowserContext;
class RenderProcessHost;
// SiteInstance interface.
// A SiteInstance represents a group of web pages that may be able to
// synchronously script each other, and thus must live in the same renderer
// process.
// We identify this group using a combination of where the page comes from
// (the site) and which tabs have references to each other (the instance).
// Here, a "site" is similar to the page's origin, but it only includes the
// registered domain name and scheme, not the port or subdomains. This accounts
// for the fact that changes to document.domain allow similar origin pages with
// different ports or subdomains to script each other. An "instance" includes
// all tabs that might be able to script each other because of how they were
// created (e.g., or targeted links). We represent instances using
// the BrowsingInstance class.
// Process models:
// In process-per-site-instance (the current default process model),
// SiteInstances are created (1) when the user manually creates a new tab
// (which also creates a new BrowsingInstance), and (2) when the user navigates
// across site boundaries (which uses the same BrowsingInstance). If the user
// navigates within a site, the same SiteInstance is used.
// (Caveat: we currently allow renderer-initiated cross-site navigations to
// stay in the same SiteInstance, to preserve compatibility in cases like
// cross-site iframes that open popups.)
// In --process-per-tab, SiteInstances are created when the user manually
// creates a new tab, but not when navigating across site boundaries (unless
// a process swap is required for security reasons, such as navigating from
// a privileged WebUI page to a normal web page). This corresponds to one
// process per BrowsingInstance.
// In --process-per-site, we consolidate all SiteInstances for a given site into
// the same process, throughout the entire browser context. This ensures that
// only one process will be used for each site.
// Each NavigationEntry for a WebContents points to the SiteInstance that
// rendered it. Each RenderViewHost also points to the SiteInstance that it is
// associated with. A SiteInstance keeps track of the number of these
// references and deletes itself when the count goes to zero. This means that
// a SiteInstance is only live as long as it is accessible, either from new
// tabs with no NavigationEntries or in NavigationEntries in the history.
class CONTENT_EXPORT SiteInstance : public base::RefCounted<SiteInstance> {
// Returns a unique ID for this SiteInstance.
virtual int32 GetId() = 0;
// Whether this SiteInstance has a running process associated with it.
// This may return true before the first call to GetProcess(), in cases where
// we use process-per-site and there is an existing process available.
virtual bool HasProcess() const = 0;
// Returns the current RenderProcessHost being used to render pages for this
// SiteInstance. If there is no RenderProcessHost (because either none has
// yet been created or there was one but it was cleanly destroyed (e.g. when
// it is not actively being used)), then this method will create a new
// RenderProcessHost (and a new ID). Note that renderer process crashes leave
// the current RenderProcessHost (and ID) in place.
// For sites that require process-per-site mode (e.g., WebUI), this will
// ensure only one RenderProcessHost for the site exists/ within the
// BrowserContext.
virtual content::RenderProcessHost* GetProcess() = 0;
// Browser context to which this SiteInstance (and all related
// SiteInstances) belongs.
virtual content::BrowserContext* GetBrowserContext() const = 0;
// Get the web site that this SiteInstance is rendering pages for.
// This includes the scheme and registered domain, but not the port.
virtual const GURL& GetSiteURL() const = 0;
// Gets a SiteInstance for the given URL that shares the current
// BrowsingInstance, creating a new SiteInstance if necessary. This ensures
// that a BrowsingInstance only has one SiteInstance per site, so that pages
// in a BrowsingInstance have the ability to script each other. Callers
// should ensure that this SiteInstance becomes ref counted, by storing it in
// a scoped_refptr. (By having this method, we can hide the BrowsingInstance
// class from the rest of the codebase.)
// TODO(creis): This may be an argument to build a pass_refptr<T> class, as
// Darin suggests.
virtual SiteInstance* GetRelatedSiteInstance(const GURL& url) = 0;
// Returns whether the given SiteInstance is in the same BrowsingInstance as
// this one. If so, JavaScript interactions that are permitted across
// origins (e.g., postMessage) should be supported.
virtual bool IsRelatedSiteInstance(const SiteInstance* instance) = 0;
// Returns the total active WebContents count for this SiteInstance and all
// related SiteInstances in the same BrowsingInstance.
virtual size_t GetRelatedActiveContentsCount() = 0;
// Factory method to create a new SiteInstance. This will create a new
// new BrowsingInstance, so it should only be used when creating a new tab
// from scratch (or similar circumstances). Callers should ensure that
// this SiteInstance becomes ref counted, by storing it in a scoped_refptr.
// The render process host factory may be nullptr. See SiteInstance
// constructor.
// TODO(creis): This may be an argument to build a pass_refptr<T> class, as
// Darin suggests.
static SiteInstance* Create(content::BrowserContext* browser_context);
// Factory method to get the appropriate SiteInstance for the given URL, in
// a new BrowsingInstance. Use this instead of Create when you know the URL,
// since it allows special site grouping rules to be applied (for example,
// to group chrome-ui pages into the same instance).
static SiteInstance* CreateForURL(
content::BrowserContext* browser_context, const GURL& url);
// Return whether both URLs are part of the same web site, for the purpose of
// assigning them to processes accordingly. The decision is currently based
// on the registered domain of the URLs (,, as well as
// the scheme (https, http). This ensures that two pages will be in
// the same process if they can communicate with other via JavaScript.
// (e.g., and have DOM access to each other
// if they both set their document.domain properties to
// Note that if the destination is a blank page, we consider that to be part
// of the same web site for the purposes for process assignment.
static bool IsSameWebSite(content::BrowserContext* browser_context,
const GURL& src_url,
const GURL& dest_url);
// Returns the site for the given URL, which includes only the scheme and
// registered domain. Returns an empty GURL if the URL has no host.
static GURL GetSiteForURL(BrowserContext* context, const GURL& url);
friend class base::RefCounted<SiteInstance>;
SiteInstance() {}
virtual ~SiteInstance() {}
} // namespace content.