Add support for providing an external file for extracting content.

components/dom_distiller/core/distiller_page.h

Index: components/dom_distiller/core/distiller_page.h
diff --git a/components/dom_distiller/core/distiller_page.h b/components/dom_distiller/core/distiller_page.h
index 74cf277935b81809bb979aae01e37bac2aa2a2d0..b3edabb96132157666e058d85d94fa6334b3bed7 100644
--- a/components/dom_distiller/core/distiller_page.h
+++ b/components/dom_distiller/core/distiller_page.h
@@ -34,6 +34,8 @@ class DistillerPage {
            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
@@ -57,6 +59,8 @@ class DistillerPage {
 
  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);
 };