cc: Move surfaces hittesting test helpers out to a separate file

cc/BUILD.gn

Index: cc/BUILD.gn
diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 605cbd418800536e5e2bfbd6551e74fc42faed2b..81faf768e0106db036c5639e85ea1f1faabd6e8e 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn
@@ -639,6 +639,10 @@ source_set("test_support") {
     "test/skia_common.h",
     "test/solid_color_content_layer_client.cc",
     "test/solid_color_content_layer_client.h",
+    "test/surface_aggregator_test_helpers.cc",
+    "test/surface_aggregator_test_helpers.h",
+    "test/surface_hittest_test_helpers.cc",
+    "test/surface_hittest_test_helpers.h",
     "test/test_context_provider.cc",
     "test/test_context_provider.h",
     "test/test_context_support.cc",
@@ -674,6 +678,8 @@ source_set("test_support") {
     "//base",
     "//base/test:test_support",
     "//base/third_party/dynamic_annotations",
+    "//cc/surfaces",
+    "//cc/surfaces:surface_id",
     "//gpu/command_buffer/client:gles2_c_lib",
     "//gpu/command_buffer/client:gles2_implementation",
     "//gpu/command_buffer/client:gl_in_process_context",
@@ -842,8 +848,6 @@ test("cc_unittests") {
     # Surfaces test files.
     "surfaces/display_scheduler_unittest.cc",
     "surfaces/display_unittest.cc",
-    "surfaces/surface_aggregator_test_helpers.cc",
-    "surfaces/surface_aggregator_test_helpers.h",
     "surfaces/surface_aggregator_unittest.cc",
     "surfaces/surface_display_output_surface_unittest.cc",
     "surfaces/surface_factory_unittest.cc",