Add support for providing an external file for extracting content.

components/dom_distiller/core/distiller_page.h

 // Copyright 2013 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 COMPONENTS_DOM_DISTILLER_CORE_DISTILLER_PAGE_H_
 #define COMPONENTS_DOM_DISTILLER_CORE_DISTILLER_PAGE_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 16 matching lines @@
 // following the state transitions described along with the class's states.
 // Constructing a DistillerPage should be cheap, as some of the instances can be
 // thrown away without ever being used.
 class DistillerPage {
  public:
   typedef base::Callback<
       void(scoped_ptr<proto::DomDistillerResult> distilled_page,
            bool distillation_successful)> DistillerPageCallback;
 
   DistillerPage();
+  // Use this constructor to override the JS that comes packaged with Chrome.
+  DistillerPage(std::string distiller_js_script);
   virtual ~DistillerPage();
 
   // Loads a URL. |OnDistillationDone| is called when the load completes or
   // fails. May be called when the distiller is idle. Callers can assume that,
   // for a given |url| and |options|, any DistillerPage implementation will
   // extract the same content.
   void DistillPage(const GURL& url,
                    const proto::DomDistillerOptions options,
                    const DistillerPageCallback& callback);
 
   // Called when the JavaScript execution completes. |page_url| is the url of
   // the distilled page. |value| contains data returned by the script.
   virtual void OnDistillationDone(const GURL& page_url,
                                   const base::Value* value);
 
  protected:
   // Called by |DistillPage| to carry out platform-specific instructions to load
   // and distill the |url| using the provided |script|. The extracted content
   // should be the same regardless of the DistillerPage implementation.
   virtual void DistillPageImpl(const GURL& url, const std::string& script) = 0;
 
  private:
   bool ready_;
+  // An optional script for overriding the JS that comes packaged with Chrome.

[cjhopman, 2015/02/05 02:09:40]

This isn't really optional, it will always hold the script to use

[nyquist, 2015/02/06 18:50:32]

Done.
Also updated the comment above the constructor to clarify the need for
$$OPTIONS.

+  std::string distiller_js_script_;
   DistillerPageCallback distiller_page_callback_;
   DISALLOW_COPY_AND_ASSIGN(DistillerPage);
 };
 
 // Factory for generating a |DistillerPage|.
 class DistillerPageFactory {
  public:
   virtual ~DistillerPageFactory();
 
   // Constructs and returns a new DistillerPage. The implementation of this
   // should be very cheap, since the pages can be thrown away without being
   // used.
   virtual scoped_ptr<DistillerPage> CreateDistillerPage(
       const gfx::Size& render_view_size) const = 0;
   virtual scoped_ptr<DistillerPage> CreateDistillerPageWithHandle(
       scoped_ptr<SourcePageHandle> handle) const = 0;
 };
 
 }  // namespace dom_distiller
 
 #endif  // COMPONENTS_DOM_DISTILLER_CORE_DISTILLER_PAGE_H_