Add support for providing an external file for extracting content.

components/resources/dom_distiller_resources.grdp

Index: components/resources/dom_distiller_resources.grdp
diff --git a/components/resources/dom_distiller_resources.grdp b/components/resources/dom_distiller_resources.grdp
index c5e0285c0a27d0b9d6344e698a6d7e6e588d5dfd..41e3e1a0406b64cada6c46d474dfd95f81217bf2 100644
--- a/components/resources/dom_distiller_resources.grdp
+++ b/components/resources/dom_distiller_resources.grdp
@@ -6,7 +6,7 @@
   <include name="IDR_DOM_DISTILLER_VIEWER_HTML" file="../dom_distiller/core/html/dom_distiller_viewer.html" type="BINDATA" />
   <include name="IDR_DOM_DISTILLER_VIEWER_JS" file="../dom_distiller/core/javascript/dom_distiller_viewer.js" type="BINDATA" />
   <if expr="not is_ios">
-    <include name="IDR_DISTILLER_JS" file="../dom_distiller/core/javascript/domdistiller.js" flattenhtml="true" type="BINDATA" />
+    <include name="IDR_DISTILLER_JS" file="../../third_party/dom_distiller_js/package/js/domdistiller_wrapped.js" type="BINDATA" />

[noyau (Ping after 24h), 2015/03/11 14:30:59]

I'm not for that change. This file needs iOS specific changes that are going to
be hard to maintain: now the ios file and the non ios file are in two different
repositories.

Instead I made a CL (https://codereview.chromium.org/995343002/) that merge the
two files in one and uses grit <if> to do the right thing, diminishing the
maintenance burden.

[cjhopman, 2015/03/12 02:03:14]

Yeah, we should definitely merge these into one file. We would like to maintain
this in the dom distiller repo because the file basically needs to stay in sync
with the api exposed there (but doesn't need to change for chrome-side changes).

noyau, are you particularly opposed to it being maintained in the other repo? my
impression is that you mostly just don't want us to be maintaining two similar,
but different, versions of it. If it's in the other repo, we would also need to
support different platforms via javascript stuff rather than grit stuff. wdyt?

   </if>
   <if expr="is_ios">
     <include name="IDR_DISTILLER_JS" file="../dom_distiller/ios/javascript/domdistiller.js" flattenhtml="true" type="BINDATA" />