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1 // Copyright 2017 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_RENDERER_UNIQUE_NAME_HELPER_H_ | |
6 #define CONTENT_RENDERER_UNIQUE_NAME_HELPER_H_ | |
7 | |
8 #include <string> | |
9 | |
10 #include "base/macros.h" | |
11 | |
12 namespace blink { | |
13 class WebFrame; | |
14 class WebLocalFrame; | |
15 } // namespace blink | |
16 | |
17 namespace content { | |
18 | |
19 class RenderFrameImpl; | |
20 | |
21 // Frame helper that manages the details of generating a quasi-stable unique | |
22 // name for the frame. The name is unique within a page, and is used for: | |
23 // - matching up session history items with recreated frames | |
24 // - layout test results | |
25 // | |
26 // Description of the current unique name format | |
27 // --------------------------------------------- | |
28 // | |
29 // Changing the format of unique name is undesirable, because it breaks | |
30 // backcompatibility of session history (which stores unique names | |
31 // generated in the past on user's disk). This incremental, | |
32 // backcompatibility-aware approach has resulted so far in the following | |
33 // rather baroque format... : | |
34 // | |
35 // uniqueName ::= <nullForMainFrame> | <assignedName> | <generatedName> | |
36 // (generatedName is used if assignedName is | |
37 // non-unique / conflicts with other frame's unique name. | |
38 // | |
39 // assignedName ::= value of iframe's name attribute | |
40 // or value assigned to window.name (*before* the first | |
41 // real commit - afterwards unique name stays immutable). | |
Charlie Reis
2017/03/20 20:11:39
minor nit: Can you fix the indent here? I'm not p
dcheng
2017/03/21 22:03:41
Done.
| |
42 // | |
43 // generatedName ::= oldGeneratedName newUniqueSuffix? | |
44 // (newUniqueSuffix is only present if oldGeneratedName was | |
45 // not unique after all) | |
46 // | |
47 // oldGeneratedName ::= "<!--framePath //" ancestorChain | |
48 // "/<!--frame" childCount "-->-->" | |
49 // (oldGeneratedName is generated by | |
50 // generateUniqueNameCandidate method). | |
51 // | |
52 // childCount ::= current number of siblings | |
53 // | |
54 // ancestorChain ::= concatenated unique names of ancestor chain, | |
55 // terminated on the first ancestor (if any) starting with | |
56 // "<!--framePath"; each ancestor's unique name is | |
57 // separated by "/" character | |
58 // ancestorChain example1: "grandparent/parent" | |
59 // (ancestor's unique names : #1--^ | #2-^ ) | |
60 // ancestorChain example2: | |
61 // "<!--framePath //foo/bar/<!--frame42-->-->/blah/foobar" | |
62 // (ancestor's unique names: | |
63 // ^--#1--^ | #2 | #3-^ ) | |
64 // | |
65 // newUniqueSuffix ::= "<!--framePosition" framePosition "/" retryNumber | |
66 // "-->" | |
67 // | |
68 // framePosition ::= "-" numberOfSiblingsBeforeChild | |
69 // [ framePosition-forParent? ] | |
70 // | |
71 // retryNumber ::= smallest non-negative integer resulting in unique name | |
72 | |
73 class UniqueNameHelper { | |
74 public: | |
75 explicit UniqueNameHelper(RenderFrameImpl* render_frame); | |
76 ~UniqueNameHelper(); | |
77 | |
78 // Returns the generated unique name. | |
79 const std::string& value() const { return unique_name_; } | |
80 | |
81 // Used to propagate an already calculated unique name. | |
82 // | |
83 // TODO(lukasza): It would be nice to assert uniqueness of the propagated | |
84 // name here but: | |
85 // 1) uniqueness is currently violated by provisional/old frame pairs. | |
86 // 2) there is an unresolved race between 2 OOPIFs, that can result in a | |
87 // non-unique unique name: see https://crbug.com/558680#c14. | |
88 void set_propagated_name(const std::string& name) { unique_name_ = name; } | |
89 | |
90 // Note: when creating a new child frame, the unique name needs to be | |
91 // calculated before the RenderFrameImpl is created. To avoid this chicken and | |
92 // egg problem, this method is static, which means that |parent| needs to be | |
93 // passed as a parameter. | |
94 static std::string GenerateNameForNewChildFrame(blink::WebFrame* parent, | |
95 const std::string& name); | |
Charlie Reis
2017/03/20 20:11:39
Please also document what we're expecting about |n
dcheng
2017/03/21 22:03:42
I've documented this centrally in RenderFrameImpl.
| |
96 | |
97 // Called after a browsing context name change to generate a new name. Note | |
98 // that this should not be called if the frame is no longer displaying the | |
99 // initial empty document, as unique name changes after that point will break | |
100 // history navigations. See https://crbug.com/607205. | |
101 void UpdateName(const std::string& name); | |
102 | |
103 private: | |
104 blink::WebLocalFrame* GetWebFrame() const; | |
105 | |
106 RenderFrameImpl* const render_frame_; | |
107 std::string unique_name_; | |
108 | |
109 DISALLOW_COPY_AND_ASSIGN(UniqueNameHelper); | |
110 }; | |
111 | |
112 } // namespace content | |
113 | |
114 #endif // CONTENT_RENDERER_UNIQUE_NAME_HELPER_H_ | |
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