Revert "Disable ExtensionServiceTest.ExternalInstallClickToRemove on Win"

This reverts commit bbc76b3b.

Reason for revert: This flakiness was caused by crrev.com/b53ca149, which was reverted in crrev.com/7cf9ce83.

Original change's description:
> Disable ExtensionServiceTest.ExternalInstallClickToRemove on Win
>
> It is flaky 
>
> Change-Id: I0a1f011768ddef79c16bd0945231fe3b96dd7146
> BUG: 1168464
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2640037
> Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
> Commit-Queue: Christos Froussios <cfroussios@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#846046}

TBR=rdevlin.cronin@chromium.org,cfroussios@chromium.org,chromium-scoped@luci-project-accounts.iam.gserviceaccount.com,cfroussios@google.com

Change-Id: Id3941aa4683d0fd7f54b734faa0d60f472a344b7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2644379Reviewed-by: David Bertoni <dbertoni@chromium.org>
Commit-Queue: David Bertoni <dbertoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846182}

chrome/browser/extensions/extension_service_unittest.cc

@@ -7375,13 +7375,7 @@ TEST_F(ExtensionServiceTest, ExternalInstallUpdatesFromWebstoreNewProfile) {
 
 // Test that clicking to remove the extension on an external install warning
 // uninstalls the extension.
-// Flaky on Win7 (dbg). http://crbug.com/1168464
-#if defined(OS_WIN) && !defined(NDEBUG)
-#define MAYBE_ExternalInstallClickToRemove DISABLED_ExternalInstallClickToRemove
-#else
-#define MAYBE_ExternalInstallClickToRemove ExternalInstallClickToRemove
-#endif
-TEST_F(ExtensionServiceTest, MAYBE_ExternalInstallClickToRemove) {
+TEST_F(ExtensionServiceTest, ExternalInstallClickToRemove) {
   FeatureSwitch::ScopedOverride prompt(
       FeatureSwitch::prompt_for_external_extensions(), true);