Move test runner to a component

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 224591faf3c10908e9f5b628aeee219c0291b674..0f946dcacf9134fc92c9699ba8c25a894e0c39f0 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -748,8 +748,8 @@ if (!is_ios) {
 
     if (is_win) {
       deps += [
+        "//components/test_runner:layout_test_helper",
         "//content/shell:crash_service",
-        "//content/shell:layout_test_helper",
       ]
     }
 
@@ -760,7 +760,7 @@ if (!is_ios) {
     if (is_mac) {
       deps += [
         "//breakpad:dump_syms($host_toolchain)",
-        "//content/shell:layout_test_helper",
+        "//components/test_runner:layout_test_helper",
       ]
     }