Remove leftover includes in safe_browsing_blocking_page_unittest.cc

It was using the SigninManager API, but the only test using it was
removed in crrev.com/c/1346400. Just removing the leftover includes.

Bug: 903881
Change-Id: Idb35dbff7a1b4f1d48140f4d2a6955cc8788dc63
Reviewed-on: https://chromium-review.googlesource.com/c/1352423Reviewed-by: Varun Khaneja <vakh@chromium.org>
Commit-Queue: Sergio Villar <svillar@igalia.com>
Cr-Commit-Position: refs/heads/master@{#611746}

chrome/browser/safe_browsing/safe_browsing_blocking_page_unittest.cc

@@ -12,7 +12,6 @@
 #include "chrome/browser/safe_browsing/test_safe_browsing_service.h"
 #include "chrome/browser/safe_browsing/ui_manager.h"
 #include "chrome/browser/signin/scoped_account_consistency.h"
-#include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/chrome_render_view_host_test_harness.h"
 #include "chrome/test/base/scoped_testing_local_state.h"
@@ -27,7 +26,6 @@
 #include "components/security_interstitials/content/security_interstitial_controller_client.h"
 #include "components/security_interstitials/core/safe_browsing_quiet_error_ui.h"
 #include "components/signin/core/browser/signin_buildflags.h"
-#include "components/signin/core/browser/signin_manager.h"
 #include "components/strings/grit/components_strings.h"
 #include "content/public/browser/browser_task_traits.h"
 #include "content/public/browser/browser_thread.h"