[Contextual Search] Add Mojo-enabled API component.

chrome/renderer/chrome_content_renderer_client.cc

Index: chrome/renderer/chrome_content_renderer_client.cc
diff --git a/chrome/renderer/chrome_content_renderer_client.cc b/chrome/renderer/chrome_content_renderer_client.cc
index 7910d84a9867a3b0e6b7b9220ddec95c07cb4469..18ac83a8ba770e5b4a1cde5d58fc81082abd5dbf 100644
--- a/chrome/renderer/chrome_content_renderer_client.cc
+++ b/chrome/renderer/chrome_content_renderer_client.cc
@@ -33,6 +33,7 @@
 #include "chrome/renderer/chrome_render_process_observer.h"
 #include "chrome/renderer/chrome_render_view_observer.h"
 #include "chrome/renderer/content_settings_observer.h"
+#include "chrome/renderer/contextualsearch/contextual_search_wrapper.h"
 #include "chrome/renderer/external_extension.h"
 #include "chrome/renderer/loadtimes_extension_bindings.h"
 #include "chrome/renderer/media/chrome_key_systems.h"
@@ -514,6 +515,12 @@ void ChromeContentRendererClient::RenderFrameCreated(
     // Only attach MainRenderFrameObserver to the main frame, since
     // we only want to log page load metrics for the main frame.
     new page_load_metrics::MetricsRenderFrameObserver(render_frame);
+
+    // Install Contextual Search support in the main frame if needed.
+    if (base::CommandLine::ForCurrentProcess()->HasSwitch(

[Donn Denman, 2015/10/28 00:26:56]

Charlie, I'm thinking that we should change this to trigger off of mojo (like
Dom Distiller) instead of a command-line flag, and that should keep us from
adding our JS API based on the render process.  I would think that then the
reusing of the process would not be an issue.  Does that sound right to you?

[Charlie Reis, 2015/10/28 19:51:44]

Scoping it to a RenderFrame isn't a bad idea, but it won't help with the concern
about compromised renderer processes.  Once a malicious page takes over a
renderer process, it can pretend to be any RenderFrame in the process.  We
assume attackers can execute arbitrary code in the renderer process.

I think you'll still need to prevent process reuse for the overlay process.

+            switches::kContextualSearchProcess)) {
+      search::ContextualSearchWrapper::Install(render_frame->GetWebFrame());
+    }
   } else {
     // Avoid any race conditions from having the browser tell subframes that
     // they're prerendering.