Only commit cookie changes in prerenders after a prerender is shown

chrome/browser/prerender/prerender_browsertest.cc

Index: chrome/browser/prerender/prerender_browsertest.cc
===================================================================
--- chrome/browser/prerender/prerender_browsertest.cc	(revision 269781)
+++ chrome/browser/prerender/prerender_browsertest.cc	(working copy)
@@ -1124,6 +1124,12 @@
     return scoped_ptr<TestPrerender>(prerenders[0]);
   }
 
+  // Navigates to a URL, unrelated to prerendering
+  void NavigateStraightToURL(const std::string dest_html_file) {
+    ui_test_utils::NavigateToURL(current_browser(),
+                                 test_server()->GetURL(dest_html_file));
+  }
+
   void NavigateToDestURL() const {
     NavigateToDestURLWithDisposition(CURRENT_TAB, true);
   }
@@ -1484,6 +1490,22 @@
                                       base::ASCIIToUTF16(page_title));
   }
 
+  void RunJSReturningString(const char* js, std::string* result) {
+    ASSERT_TRUE(
+        content::ExecuteScriptAndExtractString(
+            GetActiveWebContents(),
+            base::StringPrintf("window.domAutomationController.send(%s)",
+                               js).c_str(),
+            result));
+  }
+
+  void RunJS(const char* js) {
+    ASSERT_TRUE(content::ExecuteScript(
+        GetActiveWebContents(),
+        base::StringPrintf("window.domAutomationController.send(%s)",
+                           js).c_str()));
+  }
+
  protected:
   bool autostart_test_server_;
 
@@ -4153,6 +4175,103 @@
   histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
 }
 
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
+                       PrerenderCookieChangeConflictTest) {
+  NavigateStraightToURL(
+      "files/prerender/prerender_cookie.html?set=1&key=c&value=1");
+
+  GURL url = test_server()->GetURL(
+      "files/prerender/prerender_cookie.html?set=1&key=c&value=2");
+
+  scoped_ptr<TestPrerender> prerender =
+      ExpectPrerender(FINAL_STATUS_COOKIE_CONFLICT);
+  AddPrerender(url, 1);
+  prerender->WaitForStart();
+  prerender->WaitForLoads(1);
+  // Ensure that in the prerendered page, querying the cookie again
+  // via javascript yields the same value that was set during load.
+  EXPECT_TRUE(DidPrerenderPass(prerender->contents()->prerender_contents()));
+
+  // The prerender has loaded. Ensure that the change is not visible
+  // to visible tabs.
+  std::string value;
+  RunJSReturningString("GetCookie('c')", &value);
+  ASSERT_EQ(value, "1");
+
+  // Make a conflicting cookie change, which should cancel the prerender.
+  RunJS("SetCookie('c', '3')");
+  prerender->WaitForStop();
+}
+
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderCookieChangeUseTest) {
+  // Permit 2 concurrent prerenders.
+  GetPrerenderManager()->mutable_config().max_link_concurrency = 2;
+  GetPrerenderManager()->mutable_config().max_link_concurrency_per_launcher = 2;
+
+  // Go to a first URL setting the cookie to value "1".
+  NavigateStraightToURL(
+      "files/prerender/prerender_cookie.html?set=1&key=c&value=1");
+
+  // Prerender a URL setting the cookie to value "2".
+  GURL url = test_server()->GetURL(
+      "files/prerender/prerender_cookie.html?set=1&key=c&value=2");
+
+  scoped_ptr<TestPrerender> prerender1 = ExpectPrerender(FINAL_STATUS_USED);
+  AddPrerender(url, 1);
+  prerender1->WaitForStart();
+  prerender1->WaitForLoads(1);
+
+  // Launch a second prerender, setting the cookie to value "3".
+  scoped_ptr<TestPrerender> prerender2 =
+      ExpectPrerender(FINAL_STATUS_COOKIE_CONFLICT);
+  AddPrerender(test_server()->GetURL(
+      "files/prerender/prerender_cookie.html?set=1&key=c&value=3"), 1);
+  prerender2->WaitForStart();
+  prerender2->WaitForLoads(1);
+
+  // Both prerenders have loaded. Ensure that the visible tab is still
+  // unchanged and cannot see their changes.
+  // to visible tabs.
+  std::string value;
+  RunJSReturningString("GetCookie('c')", &value);
+  ASSERT_EQ(value, "1");
+
+  // Navigate to the prerendered URL. The first prerender should be swapped in,
+  // and the changes should now be visible. The second prerender should
+  // be cancelled due to the conflict.
+  ui_test_utils::NavigateToURLWithDisposition(
+      current_browser(),
+      url,
+      CURRENT_TAB,
+      ui_test_utils::BROWSER_TEST_NONE);
+  RunJSReturningString("GetCookie('c')", &value);
+  ASSERT_EQ(value, "2");
+  prerender2->WaitForStop();
+}
+
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
+                       PrerenderCookieChangeConflictHTTPHeaderTest) {
+  NavigateStraightToURL(
+      "files/prerender/prerender_cookie.html?set=1&key=c&value=1");
+
+  GURL url = test_server()->GetURL("set-cookie?c=2");
+  scoped_ptr<TestPrerender> prerender =
+      ExpectPrerender(FINAL_STATUS_COOKIE_CONFLICT);
+  AddPrerender(url, 1);
+  prerender->WaitForStart();
+  prerender->WaitForLoads(1);
+
+  // The prerender has loaded. Ensure that the change is not visible
+  // to visible tabs.
+  std::string value;
+  RunJSReturningString("GetCookie('c')", &value);
+  ASSERT_EQ(value, "1");
+
+  // Make a conflicting cookie change, which should cancel the prerender.
+  RunJS("SetCookie('c', '3')");
+  prerender->WaitForStop();
+}
+
 // Checks that a prerender which calls window.close() on itself is aborted.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderWindowClose) {
   DisableLoadEventCheck();