Make a mojo:apptests GN meta-target, add apptests.

Add an apptest meta-target in mojo/BUILD.gn.
Move the apptests targets specified in src/BUILD.gn.
Add the remaining apptest targets (clipboard, VM, WM).

Was limited to release, allow debug, but exclude component.
See gn_debug compile error from including component build in PS2:
  FAILED: /b/build/slave/linux_chromium_gn/build/src/buildtools/linux64/gn --root=/b/build/slave/linux_chromium_gn/build/src -q gen //out/Debug/
  ERROR at //mojo/shell/BUILD.gn:13:1: Assertion failed.
  assert(!is_component_build)

BUG=NONE
TEST=Building mojo:apptests builds all local apptest binaries (on dbg too!).
R=sky@chromium.org
TBR=ben@chromium.org

Review URL: https://codereview.chromium.org/1050233005

Cr-Commit-Position: refs/heads/master@{#325570}

BUILD.gn

@@ -684,6 +684,7 @@ group("gn_mojo_targets") {
       "//media/mojo/interfaces:interfaces_python",
       "//media/mojo/services:cdm_service",
       "//media/mojo:tests",
+      "//mojo:apptests",
       "//net/interfaces:interfaces_dart",
       "//net/interfaces:interfaces_python",
       "//third_party/mojo/src/mojo/edk/js/test:js_integration_tests",
@@ -698,12 +699,8 @@ group("gn_mojo_targets") {
       "//third_party/mojo_services/src/window_manager/public/interfaces:interfaces_python",
     ]
 
-    if (!is_debug) {
-      deps += [
-        "//mojo/services/html_viewer:apptests",
-        "//mojo/services/html_viewer:tests",
-        "//mojo/services/network:apptests",
-      ]
+    if (!is_component_build) {
+      deps += [ "//mojo/services/html_viewer:tests" ]
     }
   }
 }

mojo/BUILD.gn

@@ -39,3 +39,20 @@ group("tests") {
     "//third_party/mojo/src/mojo/edk/test:mojo_public_utility_unittests",
   ]
 }
+
+# TODO(GYP): Not included in the mojo group meta-target; missing gyp targets.
+#            See the gn_all and gn_only comments in //src/BUILD.gn.
+group("apptests") {
+  testonly = true
+  deps = []
+  if (!is_component_build) {
+    deps += [
+      "//mojo/services/clipboard:apptests",
+      "//mojo/services/html_viewer:apptests",
+      "//mojo/services/network:apptests",
+      "//mojo/services/view_manager:mojo_view_manager_client_apptests",
+      "//mojo/services/view_manager:view_manager_service_apptests",
+      "//mojo/services/window_manager:window_manager_apptests",
+    ]
+  }
+}