Renaming poorly named classes and adding missing unit tests.

chrome/renderer/prerender/prerender_dispatcher.cc

Index: chrome/renderer/prerender/prerender_dispatcher.cc
diff --git a/chrome/renderer/prerender/prerender_dispatcher.cc b/chrome/renderer/prerender/prerender_dispatcher.cc
index 84173fd444ce446cd96ffc3088347d2227732b53..01b20111cd9354e7f39831d2174d9eeded9f66b5 100644
--- a/chrome/renderer/prerender/prerender_dispatcher.cc
+++ b/chrome/renderer/prerender/prerender_dispatcher.cc
@@ -39,7 +39,7 @@ void PrerenderDispatcher::OnAddPrerenderURL(const GURL& url) {
   PrerenderMap::iterator it = prerender_urls_.find(url);
   if (it != prerender_urls_.end()) {
     DCHECK(it->second > 0);
-    it->second += 1;
+    ++it->second;
   } else {
     prerender_urls_[url] = 1;
   }
@@ -55,7 +55,7 @@ void PrerenderDispatcher::OnRemovePrerenderURL(const GURL& url) {
   if (it == prerender_urls_.end())
     return;
   DCHECK(it->second > 0);
-  it->second -= 1;
+  --it->second;
   if (it->second == 0)
     prerender_urls_.erase(it);
 }