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      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 CHROME_RENDERER_EXTENSIONS_CONTENT_WATCHER_H_
      6 #define CHROME_RENDERER_EXTENSIONS_CONTENT_WATCHER_H_
      7 
      8 #include <map>
      9 #include <string>
     10 #include <vector>
     11 
     12 #include "base/memory/scoped_ptr.h"
     13 #include "base/memory/weak_ptr.h"
     14 #include "base/strings/string_piece.h"
     15 #include "v8/include/v8.h"
     16 
     17 namespace WebKit {
     18 class WebFrame;
     19 }
     20 
     21 namespace extensions {
     22 class Dispatcher;
     23 class Extension;
     24 class NativeHandler;
     25 
     26 // Watches the content of WebFrames to notify extensions when they match various
     27 // patterns.  This class tracks the set of relevant patterns (set by
     28 // ExtensionMsg_WatchPages) and the set that match on each WebFrame, and sends a
     29 // ExtensionHostMsg_OnWatchedPageChange whenever a RenderView's set changes.
     30 //
     31 // There's one ContentWatcher per Dispatcher rather than per RenderView because
     32 // WebFrames can move between RenderViews through adoptNode.
     33 class ContentWatcher {
     34  public:
     35   explicit ContentWatcher(Dispatcher* dispatcher);
     36   ~ContentWatcher();
     37 
     38   // Returns the callback to call on a frame change.
     39   scoped_ptr<NativeHandler> MakeNatives(ChromeV8Context* context);
     40 
     41   // Handler for ExtensionMsg_WatchPages.
     42   void OnWatchPages(const std::vector<std::string>& css_selectors);
     43 
     44   // Registers the MutationObserver to call back into this object whenever the
     45   // content of |frame| changes.
     46   void DidCreateDocumentElement(WebKit::WebFrame* frame);
     47 
     48   // Scans *frame for the current set of interesting CSS selectors, and if
     49   // they've changed sends ExtensionHostMsg_OnWatchedPageChange back to the
     50   // RenderViewHost that owns the frame.
     51   void ScanAndNotify(WebKit::WebFrame* frame);
     52 
     53  private:
     54   void EnsureWatchingMutations(WebKit::WebFrame* frame);
     55 
     56   ModuleSystem* GetModuleSystem(WebKit::WebFrame* frame) const;
     57   std::vector<base::StringPiece> FindMatchingSelectors(
     58       WebKit::WebFrame* frame) const;
     59 
     60   // Given that we saw a change in the CSS selectors that |changed_frame|
     61   // matched, tell the browser about the new set of matching selectors in its
     62   // top-level page.  We filter this so that if an extension were to be granted
     63   // activeTab permission on that top-level page, we only send CSS selectors for
     64   // frames that it could run on.
     65   void NotifyBrowserOfChange(WebKit::WebFrame* changed_frame) const;
     66 
     67   base::WeakPtrFactory<ContentWatcher> weak_ptr_factory_;
     68   Dispatcher* dispatcher_;
     69 
     70   // If any of these selectors match on a page, we need to send an
     71   // ExtensionHostMsg_OnWatchedPageChange back to the browser.
     72   std::vector<std::string> css_selectors_;
     73 
     74   // Maps live WebFrames to the set of CSS selectors they match.  This lets us
     75   // traverse a top-level frame's sub-frames without rescanning them all each
     76   // time any one changes.
     77   //
     78   // The StringPieces point into css_selectors_ above, so when it changes, they
     79   // all need to be regenerated.
     80   std::map<WebKit::WebFrame*,
     81            std::vector<base::StringPiece> > matching_selectors_;
     82 };
     83 
     84 }  // namespace extensions
     85 
     86 #endif  // CHROME_RENDERER_EXTENSIONS_CONTENT_WATCHER_H_
     87