1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef CONTENT_BROWSER_BROWSING_INSTANCE_H_ 6 #define CONTENT_BROWSER_BROWSING_INSTANCE_H_ 7 8 #include "base/containers/hash_tables.h" 9 #include "base/lazy_instance.h" 10 #include "base/memory/ref_counted.h" 11 #include "content/common/content_export.h" 12 #include "content/public/browser/browser_context.h" 13 14 class GURL; 15 16 namespace content { 17 class SiteInstance; 18 class SiteInstanceImpl; 19 20 /////////////////////////////////////////////////////////////////////////////// 21 // 22 // BrowsingInstance class 23 // 24 // A browsing instance corresponds to the notion of a "unit of related browsing 25 // contexts" in the HTML 5 spec. Intuitively, it represents a collection of 26 // tabs and frames that can have script connections to each other. In that 27 // sense, it reflects the user interface, and not the contents of the tabs and 28 // frames. 29 // 30 // We further subdivide a BrowsingInstance into SiteInstances, which represent 31 // the documents within each BrowsingInstance that are from the same site and 32 // thus can have script access to each other. Different SiteInstances can 33 // safely run in different processes, because their documents cannot access 34 // each other's contents (due to the same origin policy). 35 // 36 // It is important to only have one SiteInstance per site within a given 37 // BrowsingInstance. This is because any two documents from the same site 38 // might be able to script each other if they are in the same BrowsingInstance. 39 // Thus, they must be rendered in the same process. 40 // 41 // A BrowsingInstance is live as long as any SiteInstance has a reference to 42 // it. A SiteInstance is live as long as any NavigationEntry or RenderViewHost 43 // have references to it. Because both classes are RefCounted, they do not 44 // need to be manually deleted. 45 // 46 // BrowsingInstance has no public members, as it is designed to be 47 // visible only from the SiteInstance class. To get a new 48 // SiteInstance that is part of the same BrowsingInstance, use 49 // SiteInstance::GetRelatedSiteInstance. Because of this, 50 // BrowsingInstances and SiteInstances are tested together in 51 // site_instance_unittest.cc. 52 // 53 /////////////////////////////////////////////////////////////////////////////// 54 class CONTENT_EXPORT BrowsingInstance 55 : public base::RefCounted<BrowsingInstance> { 56 protected: 57 // Create a new BrowsingInstance. 58 explicit BrowsingInstance(BrowserContext* context); 59 60 // Get the browser context to which this BrowsingInstance belongs. 61 BrowserContext* browser_context() const { return browser_context_; } 62 63 // Returns whether this BrowsingInstance has registered a SiteInstance for 64 // the site of the given URL. 65 bool HasSiteInstance(const GURL& url); 66 67 // Get the SiteInstance responsible for rendering the given URL. Should 68 // create a new one if necessary, but should not create more than one 69 // SiteInstance per site. 70 SiteInstance* GetSiteInstanceForURL(const GURL& url); 71 72 // Adds the given SiteInstance to our map, to ensure that we do not create 73 // another SiteInstance for the same site. 74 void RegisterSiteInstance(SiteInstance* site_instance); 75 76 // Removes the given SiteInstance from our map, after all references to it 77 // have been deleted. This means it is safe to create a new SiteInstance 78 // if the user later visits a page from this site, within this 79 // BrowsingInstance. 80 void UnregisterSiteInstance(SiteInstance* site_instance); 81 82 friend class SiteInstanceImpl; 83 friend class SiteInstance; 84 85 friend class base::RefCounted<BrowsingInstance>; 86 87 // Virtual to allow tests to extend it. 88 virtual ~BrowsingInstance(); 89 90 private: 91 // Map of site to SiteInstance, to ensure we only have one SiteInstance per 92 typedef base::hash_map<std::string, SiteInstance*> SiteInstanceMap; 93 94 // Common browser context to which all SiteInstances in this BrowsingInstance 95 // must belong. 96 BrowserContext* const browser_context_; 97 98 // Map of site to SiteInstance, to ensure we only have one SiteInstance per 99 // site. The site string should be the possibly_invalid_spec() of a GURL 100 // obtained with SiteInstanceImpl::GetSiteForURL. Note that this map may not 101 // contain every active SiteInstance, because a race exists where two 102 // SiteInstances can be assigned to the same site. This is ok in rare cases. 103 SiteInstanceMap site_instance_map_; 104 105 DISALLOW_COPY_AND_ASSIGN(BrowsingInstance); 106 }; 107 108 } // namespace content 109 110 #endif // CONTENT_BROWSER_BROWSING_INSTANCE_H_ 111
