headless: Make it possible to configure an HTTP proxy

headless/lib/browser/headless_web_contents_impl.cc

Index: headless/lib/browser/headless_web_contents_impl.cc
diff --git a/headless/lib/browser/headless_web_contents_impl.cc b/headless/lib/browser/headless_web_contents_impl.cc
index 869b2b12e588a6c92d427a73ec7bb0469ea6ae61..1977e7ffac218c0f2a531e6811579372f919d1fb 100644
--- a/headless/lib/browser/headless_web_contents_impl.cc
+++ b/headless/lib/browser/headless_web_contents_impl.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/memory/weak_ptr.h"
 #include "base/trace_event/trace_event.h"
+#include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
@@ -33,6 +34,12 @@ class WebContentsObserverAdapter : public content::WebContentsObserver {
     observer_->DocumentOnLoadCompletedInMainFrame();
   }
 
+  void DidFinishNavigation(
+      content::NavigationHandle* navigation_handle) override {
+    observer_->DidFinishNavigation(navigation_handle->HasCommitted() &&
+                                   !navigation_handle->IsErrorPage());
+  }
+
  private:
   HeadlessWebContents::Observer* observer_;  // Not owned.