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 265252)
+++ chrome/browser/prerender/prerender_browsertest.cc	(working copy)
@@ -1110,6 +1110,15 @@
     return scoped_ptr<TestPrerender>(prerenders[0]);
   }
 
+  // Navigates to a URL, unrelated to prerendering
+  void NavigateStraightToURL(const std::string dest_html_file) {
+    ui_test_utils::NavigateToURLWithDisposition(
+        current_browser(),
+        test_server()->GetURL(dest_html_file),
+        CURRENT_TAB,
+        ui_test_utils::BROWSER_TEST_WAIT_FOR_NAVIGATION);
+  }
+
   void NavigateToDestURL() const {
     NavigateToDestURLWithDisposition(CURRENT_TAB, true);
   }
@@ -1470,6 +1479,22 @@
                                       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_;
 
@@ -4149,6 +4174,62 @@
   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);
+
+  // 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) {
+  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_USED);
+  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");
+
+  // Navigate to the prerendered URL. The prerender should be swapped in,
+  // and the changes should now be visible.
+  ui_test_utils::NavigateToURLWithDisposition(
+      current_browser(),
+      url,
+      CURRENT_TAB,
+      ui_test_utils::BROWSER_TEST_NONE);
+  NavigateStraightToURL(
+      "files/prerender/prerender_cookie.html?set=1&key=c&value=2");
+  RunJSReturningString("GetCookie('c')", &value);
+  ASSERT_EQ(value, "2");
+}
+
 class PrerenderIncognitoBrowserTest : public PrerenderBrowserTest {
  public:
   virtual void SetUpOnMainThread() OVERRIDE {