Revert "Disable HttpCredentialCleanerTest.ReportHttpMigrationMetrics on Mac"

This reverts commit 49ad1ffd.

Reason for revert: Stack trace did not capture the problematic root cause. http://crrev.com/9d87634b53d8403be8b0b7364e1ff3c405bf57fd should help but we need another flake.

Original change's description:
> Disable HttpCredentialCleanerTest.ReportHttpMigrationMetrics on Mac
> 
> TBR=hbos@chromium.org
> NOTRY=true
> 
> Bug: 1010016
> Change-Id: Ifff6105c6f46a35d8248f1c5c70237a104e8d714
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1833311
> Reviewed-by: Xida Chen <xidachen@chromium.org>
> Commit-Queue: Xida Chen <xidachen@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#701542}

TBR=hbos@chromium.org,xidachen@chromium.org

Change-Id: Id47dcb0001c3079c5d24fbaf08097e02845a050c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1010016
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1834188Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Dominic Battré <battre@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701926}

components/password_manager/core/browser/http_credentials_cleaner_unittest.cc

@@ -12,7 +12,6 @@
 #include "base/test/metrics/histogram_tester.h"
 #include "base/test/task_environment.h"
 #include "base/time/time.h"
-#include "build/build_config.h"
 #include "components/password_manager/core/browser/password_manager_util.h"
 #include "components/password_manager/core/browser/test_password_store.h"
 #include "components/password_manager/core/common/password_manager_pref_names.h"
@@ -124,12 +123,7 @@ class HttpCredentialCleanerTest : public ::testing::TestWithParam<TestCase> {
   DISALLOW_COPY_AND_ASSIGN(HttpCredentialCleanerTest);
 };
 
-#if defined(OS_MACOSX)
-#define MAYBE_ReportHttpMigrationMetrics DISABLED_ReportHttpMigrationMetrics
-#else
-#define MAYBE_ReportHttpMigrationMetrics ReportHttpMigrationMetrics
-#endif
-TEST_P(HttpCredentialCleanerTest, MAYBE_ReportHttpMigrationMetrics) {
+TEST_P(HttpCredentialCleanerTest, ReportHttpMigrationMetrics) {
   struct Histogram {
     bool test_hsts_enabled;
     HttpCredentialType test_type;