[translate] Defer start of translate ranker model load to first use.

components/translate/core/browser/translate_ranker_impl.cc

Index: components/translate/core/browser/translate_ranker_impl.cc
diff --git a/components/translate/core/browser/translate_ranker_impl.cc b/components/translate/core/browser/translate_ranker_impl.cc
index 1c84e8461c8a012879413aa0eb2e5cfc5d3f9112..b25706f858230526de57fb164fdd8e8f94e77639 100644
--- a/components/translate/core/browser/translate_ranker_impl.cc
+++ b/components/translate/core/browser/translate_ranker_impl.cc
@@ -156,8 +156,6 @@ TranslateRankerImpl::TranslateRankerImpl(const base::FilePath& model_path,
         base::Bind(&TranslateRankerImpl::OnModelAvailable,
                    weak_ptr_factory_.GetWeakPtr()),
         model_path, model_url, kUmaPrefix);
-    // Kick off the initial load from cache.
-    model_loader_->NotifyOfRankerActivity();
   }
 }