[Extensions] Re-enable some Resource Request Policy tests.

These tests were disabled on on Window and/or Mac for being
flaky. They passed 3000 iterations on the bots with no
issues.

Bug: 122154, 238733
Change-Id: I4aeeeddcee340837651105c6e703f4100790e6b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2411405Reviewed-by: Kelvin Jiang <kelvinjiang@chromium.org>
Commit-Queue: David Bertoni <dbertoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810344}

chrome/browser/extensions/extension_resource_request_policy_apitest.cc

@@ -229,27 +229,14 @@ IN_PROC_BROWSER_TEST_F(ExtensionResourceRequestPolicyTest, Audio) {
       << message_;
 }
 
-#if defined(OS_MAC) || defined(OS_WIN)
-// http://crbug.com/238733 - Video is flaky on Mac and Win.
-#define MAYBE_Video DISABLED_Video
-#else
-#define MAYBE_Video Video
-#endif
-
-IN_PROC_BROWSER_TEST_F(ExtensionResourceRequestPolicyTest, MAYBE_Video) {
+IN_PROC_BROWSER_TEST_F(ExtensionResourceRequestPolicyTest, Video) {
   EXPECT_TRUE(RunExtensionSubtest(
       "extension_resource_request_policy/extension2", "video.html"))
       << message_;
 }
 
-// This test times out regularly on win_rel trybots. See http://crbug.com/122154
-#if defined(OS_WIN)
-#define MAYBE_WebAccessibleResources DISABLED_WebAccessibleResources
-#else
-#define MAYBE_WebAccessibleResources WebAccessibleResources
-#endif
 IN_PROC_BROWSER_TEST_F(ExtensionResourceRequestPolicyTest,
-                       MAYBE_WebAccessibleResources) {
+                       WebAccessibleResources) {
   std::string result;
   ASSERT_TRUE(LoadExtension(test_data_dir_
       .AppendASCII("extension_resource_request_policy")