Remove HeadlessBrowserImplForTest

It's a no-op anyway.

Change-Id: I9a2183e8ab3e2082848ac888496345f50df87617
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4175974
Reviewed-by: Peter Kvitek <kvitekp@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1094292}

headless/test/headless_test_launcher.cc

@@ -6,6 +6,7 @@
 
 #include "base/command_line.h"
 #include "base/functional/bind.h"
+#include "base/functional/callback_helpers.h"
 #include "base/test/launcher/test_launcher.h"
 #include "build/build_config.h"
 #include "content/public/test/content_test_suite_base.h"
@@ -22,19 +23,6 @@
 namespace headless {
 namespace {
 
-class HeadlessBrowserImplForTest : public HeadlessBrowserImpl {
- public:
-  explicit HeadlessBrowserImplForTest()
-      : HeadlessBrowserImpl(base::BindOnce(&HeadlessBrowserImplForTest::OnStart,
-                                           base::Unretained(this))) {}
-
-  HeadlessBrowserImplForTest(const HeadlessBrowserImplForTest&) = delete;
-  HeadlessBrowserImplForTest& operator=(const HeadlessBrowserImplForTest&) =
-      delete;
-
-  void OnStart(HeadlessBrowser* browser) { EXPECT_EQ(this, browser); }
-};
-
 class HeadlessTestLauncherDelegate : public content::TestLauncherDelegate {
  public:
   HeadlessTestLauncherDelegate() = default;
@@ -56,7 +44,7 @@ class HeadlessTestLauncherDelegate : public content::TestLauncherDelegate {
  protected:
   content::ContentMainDelegate* CreateContentMainDelegate() override {
     return new HeadlessContentMainDelegate(
-        std::make_unique<HeadlessBrowserImplForTest>());
+        std::make_unique<HeadlessBrowserImpl>(base::DoNothing()));
   }
 };