Remove race in DeclarativeContentApiTest.RulesPersistence test

chrome/browser/extensions/api/declarative_content/declarative_content_apitest.cc

Index: chrome/browser/extensions/api/declarative_content/declarative_content_apitest.cc
diff --git a/chrome/browser/extensions/api/declarative_content/declarative_content_apitest.cc b/chrome/browser/extensions/api/declarative_content/declarative_content_apitest.cc
index f21802c626adc8c2804b2c9315ba2ed1f56e75ab..6407a9a1f7a5cfa3dbc03dabbc648ca3849ecb13 100644
--- a/chrome/browser/extensions/api/declarative_content/declarative_content_apitest.cc
+++ b/chrome/browser/extensions/api/declarative_content/declarative_content_apitest.cc
@@ -485,15 +485,17 @@ IN_PROC_BROWSER_TEST_F(DeclarativeContentApiTest, PRE_RulesPersistence) {
 // Reloads the extension from PRE_RulesPersistence and checks that the rules
 // continue to work as expected after being persisted and reloaded.
 IN_PROC_BROWSER_TEST_F(DeclarativeContentApiTest, RulesPersistence) {
-  ExtensionTestMessageListener ready("second run ready", false);
-  ExtensionTestMessageListener ready_split("second run ready (split)", false);
-  ASSERT_TRUE(ready.WaitUntilSatisfied());
-
   ExtensionRegistry* registry = ExtensionRegistry::Get(profile());
+  const base::FilePath path = test_data_dir_.
+      AppendASCII("declarative_content").AppendASCII("persistence");
   const Extension* extension =
-      GetExtensionByPath(registry->enabled_extensions(),
-                         test_data_dir_.AppendASCII("declarative_content")
-                         .AppendASCII("persistence"));
+      GetExtensionByPath(registry->enabled_extensions(), path);
+
+  if (!extension) {
+    ExtensionTestMessageListener ready("second run ready", false);
+    ASSERT_TRUE(ready.WaitUntilSatisfied());
+    extension = GetExtensionByPath(registry->enabled_extensions(), path);
+  }
 
   // Check non-incognito browser.
   content::WebContents* const tab =
@@ -513,6 +515,7 @@ IN_PROC_BROWSER_TEST_F(DeclarativeContentApiTest, RulesPersistence) {
   EXPECT_FALSE(page_action->GetIsVisible(tab_id));
 
   // Check incognito browser.
+  ExtensionTestMessageListener ready_split("second run ready (split)", false);
   Browser* incognito_browser = CreateIncognitoBrowser();
   ASSERT_TRUE(ready_split.WaitUntilSatisfied());
   content::WebContents* const incognito_tab =