Fix flakiness in FlashPermissionBrowserTest.BlockFileURL with PlzNavigate after r460581.

chrome/browser/plugins/flash_permission_browsertest.cc

Index: chrome/browser/plugins/flash_permission_browsertest.cc
diff --git a/chrome/browser/plugins/flash_permission_browsertest.cc b/chrome/browser/plugins/flash_permission_browsertest.cc
index 9c8d56cf8a6b740cc58edcc463cd75a86df2f187..651516128f1e4eb788fc91b3ddd372de7b51ecea 100644
--- a/chrome/browser/plugins/flash_permission_browsertest.cc
+++ b/chrome/browser/plugins/flash_permission_browsertest.cc
@@ -73,6 +73,10 @@ class FlashPermissionBrowserTest : public PermissionsBrowserTest {
       EXPECT_TRUE(reload_waiter.Wait());
     } else {
       EXPECT_TRUE(RunScriptReturnBool("triggerPrompt();"));
+      // Make a round trip to the renderer to flush any old did stop IPCs,
+      // otherwise they can race with the next navigation and cause it to be
+      // cancelled if it's the same URL.
+      EXPECT_TRUE(ExecuteScript(GetWebContents(), std::string()));
     }
   }
 
@@ -102,9 +106,7 @@ IN_PROC_BROWSER_TEST_F(FlashPermissionBrowserTest, CommonFailsIfDismissed) {
   CommonFailsIfDismissed();
 }
 
-// https://crbug.com/706780
-IN_PROC_BROWSER_TEST_F(FlashPermissionBrowserTest,
-                       DISABLED_CommonFailsIfBlocked) {
+IN_PROC_BROWSER_TEST_F(FlashPermissionBrowserTest, CommonFailsIfBlocked) {
   CommonFailsIfBlocked();
 }
 
@@ -206,8 +208,7 @@ IN_PROC_BROWSER_TEST_F(FlashPermissionBrowserTest, AllowFileURL) {
   EXPECT_TRUE(FeatureUsageSucceeds());
 }
 
-// Failing often. http://crbug.com/706780.
-IN_PROC_BROWSER_TEST_F(FlashPermissionBrowserTest, DISABLED_BlockFileURL) {
+IN_PROC_BROWSER_TEST_F(FlashPermissionBrowserTest, BlockFileURL) {
   base::FilePath test_path;
   PathService::Get(chrome::DIR_TEST_DATA, &test_path);
   ui_test_utils::NavigateToURL(