Index: content/renderer/unique_name_helper.h |
diff --git a/content/renderer/unique_name_helper.h b/content/renderer/unique_name_helper.h |
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+// Copyright 2017 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_RENDERER_UNIQUE_NAME_HELPER_H_ |
+#define CONTENT_RENDERER_UNIQUE_NAME_HELPER_H_ |
+ |
+#include <string> |
+ |
+#include "base/macros.h" |
+ |
+namespace blink { |
+class WebFrame; |
+class WebLocalFrame; |
+} // namespace blink |
+ |
+namespace content { |
+ |
+class RenderFrameImpl; |
+ |
+// Frame helper that manages the details of generating a quasi-stable unique |
+// name for the frame. The name is unique within a page, and is used for: |
+// - matching up session history items with recreated frames |
+// - layout test results |
+// |
+// Description of the current unique name format |
+// --------------------------------------------- |
+// Changing the format of unique name has a high cost, because it breaks |
+// backwards compatibility of session history (which stores unique names |
+// generated in the past on user's disk). The evolution of unique name in a |
+// mostly backwards-compatible way has resulted in the rather baroque format... |
+// |
+// uniqueName ::= <nullForMainFrame> | <assignedName> | <generatedName> |
+// Note: generatedName is used if assignedName is non-unique / conflicts with |
+// other frame's unique name. |
+// |
+// assignedName ::= value of iframe's name attribute |
+// or value assigned to window.name |
+// Note: The name must be assigned *before* the first real commit: afterwards, |
+// the unique name is immutable. |
+// |
+// generatedName ::= oldGeneratedName newUniqueSuffix? |
+// Note: newUniqueSuffix is only present if oldGeneratedName is not unique. |
+// |
+// oldGeneratedName ::= "<!--framePath //" ancestorChain |
+// "/<!--frame" childCount "-->-->" |
+// Note: oldGeneratedName is generated by the internal GenerateCandidate() |
+// method. |
+// |
+// childCount ::= current number of siblings |
+// |
+// ancestorChain ::= concatenated unique names of ancestor chain, |
+// terminated on the first ancestor (if any) starting with |
+// "<!--framePath"; each ancestor's unique name is |
+// separated by "/" character |
+// Note: Two examples are provided below, with each portion of the name from a |
+// distinct ancestor annotated. |
+// |
+// Example ancestor chain #1: |
+// "grandparent/parent" |
+// | #1 | #2 | |
+// Example ancestor chain #2: |
+// "<!--framePath //foo/bar/<!--frame42-->-->/blah/foobar" |
+// | #1 | #2 | #3 | |
+// |
+// newUniqueSuffix ::= "<!--framePosition" framePosition "/" retryNumber "-->" |
+// |
+// framePosition ::= "-" numberOfSiblingsBeforeChild |
+// [ framePosition-forParent? ] |
+// |
+// retryNumber ::= smallest non-negative integer resulting in unique name |
+class UniqueNameHelper { |
+ public: |
+ explicit UniqueNameHelper(RenderFrameImpl* render_frame); |
+ ~UniqueNameHelper(); |
+ |
+ // Returns the generated unique name. |
+ const std::string& value() const { return unique_name_; } |
+ |
+ // Used to propagate an already calculated unique name. |
+ // |
+ // TODO(lukasza): It would be nice to assert uniqueness of the propagated |
+ // name here but: |
+ // 1) uniqueness is currently violated by provisional/old frame pairs. |
+ // 2) there is an unresolved race between 2 OOPIFs, that can result in a |
+ // non-unique unique name: see https://crbug.com/558680#c14. |
+ void set_propagated_name(const std::string& name) { unique_name_ = name; } |
+ |
+ // Note: when creating a new child frame, the unique name needs to be |
+ // calculated before the RenderFrameImpl is created. To avoid this chicken and |
+ // egg problem, this method is static, which means that |parent| needs to be |
+ // passed as a parameter. |
+ static std::string GenerateNameForNewChildFrame(blink::WebFrame* parent, |
+ const std::string& name); |
+ |
+ // Called after a browsing context name change to generate a new name. Note |
+ // that this should not be called if the frame is no longer displaying the |
+ // initial empty document, as unique name changes after that point will break |
+ // history navigations. See https://crbug.com/607205. |
+ void UpdateName(const std::string& name); |
+ |
+ private: |
+ blink::WebLocalFrame* GetWebFrame() const; |
+ |
+ RenderFrameImpl* const render_frame_; |
+ std::string unique_name_; |
+ |
+ DISALLOW_COPY_AND_ASSIGN(UniqueNameHelper); |
+}; |
+ |
+} // namespace content |
+ |
+#endif // CONTENT_RENDERER_UNIQUE_NAME_HELPER_H_ |