Only trigger navigation in distiller if in print preview

chrome/browser/ui/webui/print_preview/print_preview_distiller.cc

Index: chrome/browser/ui/webui/print_preview/print_preview_distiller.cc
diff --git a/chrome/browser/ui/webui/print_preview/print_preview_distiller.cc b/chrome/browser/ui/webui/print_preview/print_preview_distiller.cc
index 6dc6db85ded55449c6c8878d80e4c6678a2554e5..8622262adc9660bb34828add5a1ff93e3ad2fa3b 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_distiller.cc
+++ b/chrome/browser/ui/webui/print_preview/print_preview_distiller.cc
@@ -136,6 +136,13 @@ class PrintPreviewDistiller::WebContentsDelegateImpl
         render_frame_host->GetRoutingID(), true));
   }
 
+  void DidFinishLoad(content::RenderFrameHost* render_frame_host,
+                     const GURL& validated_url) override {
+     // Notify distiller that print preview is using it.
+     dom_distiller::RunIsolatedJavaScript(web_contents()->GetMainFrame(),
+        "var is_print_preview_distiller = true;");

[Bernhard Bauer, 2016/04/25 15:36:38]

Nit: Arguments should be aligned if they're broken across multiple lines, so you
should break before web_contents->GetMainFrame() and indent those four spaces.
Or just use clang-format :)

Also, I would do the Javascript call via a static method.

[mdjones, 2016/04/25 16:33:13]

Done.

[Bernhard Bauer, 2016/04/25 17:30:31]

Sorry, too many nested languages ;-) What I meant was, expose the Javascript
functionality via a static method that you would call from here (instead of
directly accessing the variable).

[mdjones, 2016/04/25 18:24:07]

Reverted to just fix indent. The problem is that the script is not evaluated
until later, so the function won't be defined by the time I call it here.

+  }
+
   void DoPrintPreview() {
     RenderViewHost* rvh = web_contents()->GetRenderViewHost();
     rvh->Send(new PrintMsg_InitiatePrintPreview(rvh->GetRoutingID(), false));