site_instance_group.h | Explore in Territory

// Copyright 2021 The Chromium Authors
// 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_GROUP_H_
#define CONTENT_BROWSER_SITE_INSTANCE_GROUP_H_

#include "base/memory/raw_ptr.h"
#include "base/memory/ref_counted.h"
#include "base/memory/safe_ref.h"
#include "base/memory/scoped_refptr.h"
#include "base/observer_list.h"
#include "base/types/id_type.h"
#include "base/unguessable_token.h"
#include "content/browser/browsing_instance.h"
#include "content/browser/renderer_host/agent_scheduling_group_host.h"
#include "content/browser/security/coop/coop_related_group.h"
#include "content/common/content_export.h"
#include "content/public/browser/browsing_instance_id.h"
#include "content/public/browser/render_process_host_observer.h"
#include "content/public/browser/site_instance.h"
#include "third_party/perfetto/include/perfetto/tracing/traced_proto.h"

namespace perfetto::protos::pbzero {
class SiteInstanceGroup;
}  // namespace perfetto::protos::pbzero

namespace content {

class BrowserContext;
class RenderProcessHost;
class SiteInstance;
class SiteInstanceImpl;
struct ChildProcessTerminationInfo;

// A SiteInstanceGroup represents one view of a browsing context group's frame
// trees within a renderer process. It provides a tuning knob, allowing the
// number of groups to vary (for process allocation and
// painting/input/scheduling decisions) without affecting the number of security
// principals that are tracked with SiteInstances.
//
// Similar to layers composing an image from many colors, a set of
// SiteInstanceGroups compose a web page from many renderer processes. Each
// group represents one renderer process' view of a browsing context group,
// containing both local frames (organized into widgets of contiguous frames)
// and proxies for frames in other groups or processes.
//
// The documents in the local frames of a group are organized into
// SiteInstances, representing an atomic group of similar origin documents that
// can access each other directly. A group contains all the documents of one or
// more SiteInstances, all belonging to the same browsing context group (aka
// BrowsingInstance). Each browsing context group has its own set of
// SiteInstanceGroups.
//
// A SiteInstanceGroup is used for generating painted surfaces, directing input
// events, and facilitating communication between frames in different groups.
// The browser process coordinates activities across groups to produce a full
// web page.
//
// A SiteInstanceGroup always has a RenderProcessHost. If the RenderProcessHost
// itself (and not just the renderer process) goes away, then all
// RenderFrameHosts, RenderFrameProxyHosts, and workers using it are gone, and
// the SiteInstanceGroup itself goes away as well. SiteInstances in the group
// may outlive this (e.g., when kept alive by NavigationEntry), in which case
// they will get a new SiteInstanceGroup the next time one is needed.
// SiteInstanceGroups are refcounted by the SiteInstances using them, allowing
// for flexible policies. Currently, each SiteInstanceGroup has exactly one
// SiteInstance. See crbug.com/1195535.
class CONTENT_EXPORT SiteInstanceGroup
    : public base::RefCounted<SiteInstanceGroup>,
      public RenderProcessHostObserver { … };

}  // namespace content

#endif  // CONTENT_BROWSER_SITE_INSTANCE_GROUP_H_
chromium/content/browser/site_instance_group.h
