Convert visitedlink to use mojo.

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 66b45649872811a124487e67c268cd0143f5d858..93b290ab63c95b8a0e22053b8d3189d6a8e99e6b 100644
--- a/chrome/renderer/chrome_content_renderer_client.cc
+++ b/chrome/renderer/chrome_content_renderer_client.cc
@@ -361,7 +361,6 @@ void ChromeContentRendererClient::RenderThreadStarted() {
     thread->AddObserver(spellcheck_.get());
   }
 #endif
-  visited_link_slave_.reset(new visitedlink::VisitedLinkSlave());
 #if defined(FULL_SAFE_BROWSING)
   phishing_classifier_.reset(safe_browsing::PhishingClassifierFilter::Create());
 #endif
@@ -377,7 +376,6 @@ void ChromeContentRendererClient::RenderThreadStarted() {
 #if defined(FULL_SAFE_BROWSING)
   thread->AddObserver(phishing_classifier_.get());
 #endif
-  thread->AddObserver(visited_link_slave_.get());
   thread->AddObserver(prerender_dispatcher_.get());
   thread->AddObserver(subresource_filter_ruleset_dealer_.get());
   thread->AddObserver(SearchBouncer::GetInstance());
@@ -1148,11 +1146,12 @@ bool ChromeContentRendererClient::WillSendRequest(
 
 unsigned long long ChromeContentRendererClient::VisitedLinkHash(
     const char* canonical_url, size_t length) {
-  return visited_link_slave_->ComputeURLFingerprint(canonical_url, length);
+  return chrome_observer_->visited_link_slave()->ComputeURLFingerprint(
+      canonical_url, length);
 }
 
 bool ChromeContentRendererClient::IsLinkVisited(unsigned long long link_hash) {
-  return visited_link_slave_->IsVisited(link_hash);
+  return chrome_observer_->visited_link_slave()->IsVisited(link_hash);
 }
 
 blink::WebPrescientNetworking*