Fix flaky DeclarativeApiTest.PersistRules with network service

Add a flush because of http://crrev.com/c/1139048.

Bug: 347159
Change-Id: Ia134666ecbf82ae99d429522178f605b009b40eb
Reviewed-on: https://chromium-review.googlesource.com/1187375Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585888}

chrome/browser/extensions/api/declarative/declarative_apitest.cc

@@ -151,13 +151,10 @@ IN_PROC_BROWSER_TEST_F(DeclarativeApiTest, PRE_PersistRules) {
   ASSERT_TRUE(RunExtensionTest("declarative/redirect_to_data")) << message_;
 }
 
-// Disabled on Linux for flakiness: https://crbug.com/347159
-#if defined(OS_LINUX)
-#define MAYBE_PersistRules DISABLED_PersistRules
-#else
-#define MAYBE_PersistRules PersistRules
-#endif
-IN_PROC_BROWSER_TEST_F(DeclarativeApiTest, MAYBE_PersistRules) {
+IN_PROC_BROWSER_TEST_F(DeclarativeApiTest, PersistRules) {
+  // Wait for declarative rules to be set up from PRE test.
+  content::BrowserContext::GetDefaultStoragePartition(profile())
+      ->FlushNetworkInterfaceForTesting();
   ui_test_utils::NavigateToURL(browser(), GURL(kArbitraryUrl));
   EXPECT_EQ(kTestTitle, GetTitle());
 }

chrome/test/data/extensions/api_test/declarative/redirect_to_data/background.js

@@ -28,10 +28,6 @@ function report(details) {
   }
 }
 
-chrome.runtime.onInstalled.addListener(function(details) {
-  chrome.declarativeWebRequest.onRequest.addRules([rule], report);
-});
-
 var activeTabId;
 
 function navigateAndWait(url, callback) {
@@ -60,7 +56,11 @@ chrome.test.runTests([
       }))
   },
   function checkTitle() {
-    navigateAndWait('http://www.example.com',
-                    chrome.test.callbackPass(checkTitleCallback));
+    chrome.declarativeWebRequest.onRequest.addRules([rule],
+      chrome.test.callbackPass(function(details) {
+        report(details);
+        navigateAndWait('http://www.example.com',
+                        chrome.test.callbackPass(checkTitleCallback));
+      }));
   }
 ]);