[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 1a2aebdc773dabb5fd39ae0531f76a41d1624ca4..5d05399f3b9136a7a82fb008ff23be1c3f9e175c 100644
--- a/chrome/renderer/chrome_content_renderer_client.cc
+++ b/chrome/renderer/chrome_content_renderer_client.cc
@@ -34,6 +34,7 @@
 #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"
@@ -558,6 +559,12 @@ 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(
+            switches::kContextualSearchProcess)) {

[pedro (no code reviews), 2015/10/20 01:24:41]

Is there a better way to identify a Contextual Search process? Checking for the
command line flag seems brittle.

[Donn Denman, 2015/10/20 21:56:46]

No better way that I know of.  I don't think it's brittle since there's a
dedicated flag for this, but it did seem hacky to me when I first saw it in use.

There are advantages to this approch, the main ones being that we're guaranteed
to get the setting established before renderer startup, and that it's fairly
widely used, IMHO.  

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