Make mojo/application:test_support a group target.

The [data_]deps of source_set dependencies aren't built.
The group target type works as I'd expect; see bug for details.

This is still a GN bug(?) workaround, but a cleaner one.

BUG=477104
TEST=Building mojo/services/html_viewer:apptest builds mojo_shell
R=sky@chromium.org

Review URL: https://codereview.chromium.org/1053493003

Cr-Commit-Position: refs/heads/master@{#325482}

mojo/application/BUILD.gn

@@ -35,7 +35,7 @@ source_set("content_handler") {
   ]
 }
 
-source_set("test_support") {
+source_set("test_support_source_set") {
   testonly = true
   sources = [
     "application_test_base_chromium.cc",
@@ -52,8 +52,16 @@ source_set("test_support") {
     "//third_party/mojo/src/mojo/public/cpp/system",
     "//testing/gtest",
   ]
+}
+
+# This group wraps the source_set above, so building any apptest that depends
+# on this target also builds this target's data_deps; see crbug.com/477104.
+group("test_support") {
+  testonly = true
+  public_deps = [
+    ":test_support_source_set",
+  ]
 
-  # TODO(msw): Any apptest target should build mojo shell; see crbug.com/477104.
   data_deps = []
   if (is_android) {
     data_deps += [ "//mojo/android" ]

mojo/services/html_viewer/BUILD.gn

@@ -233,13 +233,4 @@ mojo_native_application("apptests") {
     "//net:test_support",
     "//testing/gtest",
   ]
-
-  # TODO(msw): Move this to mojo/application:test_support; see crbug.com/477104.
-  data_deps = []
-  if (is_android) {
-    data_deps += [ "//mojo/android" ]
-  }
-  if (!is_component_build) {
-    data_deps += [ "//mojo/shell:mojo_shell" ]
-  }
 }

mojo/services/network/BUILD.gn

@@ -127,13 +127,4 @@ mojo_native_application("apptests") {
     "//third_party/mojo/src/mojo/public/cpp/bindings",
     "//third_party/mojo/src/mojo/public/cpp/bindings:callback",
   ]
-
-  # TODO(msw): Move this to mojo/application:test_support; see crbug.com/477104.
-  data_deps = []
-  if (is_android) {
-    data_deps += [ "//mojo/android" ]
-  }
-  if (!is_component_build) {
-    data_deps += [ "//mojo/shell:mojo_shell" ]
-  }
 }