Guard against duplicate adds in PrerenderLinkManager.

chrome/browser/prerender/prerender_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/command_line.h"
 #include "base/format_macros.h"
 #include "base/memory/scoped_vector.h"
 #include "base/message_loop.h"
 #include "base/stringprintf.h"
 #include "base/time.h"
@@ skipping 294 matching lines @@
   }
 
   void SetConcurrency(size_t concurrency) {
     prerender_manager()->mutable_config().max_link_concurrency_per_launcher =
         concurrency;
     prerender_manager()->mutable_config().max_link_concurrency =
         std::max(prerender_manager()->mutable_config().max_link_concurrency,
                  concurrency);
   }
 
   bool IsEmptyPrerenderLinkManager() {

[mmenke, 2013/02/14 16:48:12]

While you're here, this could be const, too.  Since this is a release blocker
being merged, feel free not to worry about it in this CL, just thought I'd
mention it.

     return prerender_link_manager_->IsEmpty();
   }
 
+  size_t CountAllLinkPrerenders() {

[mmenke, 2013/02/14 16:48:12]

nit:  const?

+    return prerender_link_manager_->prerenders_.size();
+  }
+
   int last_prerender_id() const {
     return last_prerender_id_;
   }
 
   int GetNextPrerenderID() {
     return ++last_prerender_id_;
   }
 
   bool LauncherHasRunningPrerender(int child_id, int prerender_id) {
     PrerenderLinkManager::LinkPrerender* prerender =
@@ skipping 58 matching lines @@
           url,
           FINAL_STATUS_MANAGER_SHUTDOWN);
   EXPECT_TRUE(AddSimplePrerender(url));
   EXPECT_EQ(prerender_contents1,
             prerender_manager()->next_prerender_contents());
   EXPECT_FALSE(prerender_contents1->prerendering_has_started());
 
   ASSERT_EQ(prerender_contents, prerender_manager()->FindAndUseEntry(url));
 }
 
+// Makes sure that we do not create two running prerender entries for the same
+// launcher and prerender id.
+TEST_F(PrerenderTest, DoubleAddTest) {
+  SetConcurrency(2);
+
+  GURL url("http://www.google.com/");
+  DummyPrerenderContents* prerender_contents =
+      prerender_manager()->CreateNextPrerenderContents(
+          url,
+          FINAL_STATUS_USED);
+  EXPECT_TRUE(AddSimplePrerender(url));
+  EXPECT_TRUE(prerender_contents->prerendering_has_started());
+  EXPECT_EQ(1u, CountAllLinkPrerenders());
+
+  GURL url2("http://www.notgoogle.com/");
+  prerender_link_manager()->OnAddPrerender(kDefaultChildId,
+                                           last_prerender_id(),
+                                           url, content::Referrer(),
+                                           kSize, kDefaultRenderViewRouteId);
+  // The second add had the same launcher and prerender_id as a running
+  // prerender, so it should have done nothing.
+  EXPECT_EQ(1u, CountAllLinkPrerenders());
+  ASSERT_EQ(prerender_contents, prerender_manager()->FindAndUseEntry(url));
+  EXPECT_TRUE(IsEmptyPrerenderLinkManager());
+}
+
 // Ensure that we expire a prerendered page after the max. permitted time.
 TEST_F(PrerenderTest, ExpireTest) {
   GURL url("http://www.google.com/");
   DummyPrerenderContents* prerender_contents =
       prerender_manager()->CreateNextPrerenderContents(
           url,
           FINAL_STATUS_TIMED_OUT);
   DummyPrerenderContents* null = NULL;
   EXPECT_TRUE(AddSimplePrerender(url));
   EXPECT_EQ(null, prerender_manager()->next_prerender_contents());
@@ skipping 1007 matching lines @@
   EXPECT_EQ(null, prerender_manager()->FindEntry(second_url));
 
   // The first prerender should have died, giving life to the second one.
   prerender_manager()->AdvanceTimeTicks(wait_for_first_prerender_to_expire);
   EXPECT_EQ(null, prerender_manager()->FindEntry(first_url));
   EXPECT_EQ(second_prerender_contents,
             prerender_manager()->FindAndUseEntry(second_url));
 }
 
 }  // namespace prerender