[Fuchsia] Add gfx_tests sandbox config

Since fefeda7b ("[Fuchsia] Remove unused services from test sandbox
CMX fragment."), we can't run any graphics tests because the sandbox does
not allow access to the requisite services.

Add a new sandbox config for these cases.

Bug: 766360

Change-Id: Ic09d3ce09947a348830d95827e965e7b8b7a442e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1756386
Commit-Queue: Michael Spang <spang@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735159}

build/config/fuchsia/gfx_tests.cmx

+{
+  "sandbox": {
+    "features": [
+      "isolated-persistent-storage",
+      "isolated-temp",
+      "vulkan"
+    ],
+    "dev": [
+      "null",
+      "zero"
+    ],
+    "services": [
+      "fuchsia.fonts.Provider",
+      "fuchsia.logger.Log",
+      "fuchsia.logger.LogSink",
+      "fuchsia.process.Launcher",
+      "fuchsia.sys.Environment",
+      "fuchsia.sys.Loader",
+      "fuchsia.sysmem.Allocator",
+      "fuchsia.ui.policy.Presenter",
+      "fuchsia.ui.scenic.Scenic",
+      "fuchsia.vulkan.loader.Loader"
+    ]
+  }
+}

ui/ozone/demo/BUILD.gn

@@ -106,6 +106,7 @@ if (is_fuchsia) {
     testonly = true
     binary = ":ozone_demo"
     package_name_override = "ozone_demo"
+    manifest = "//build/config/fuchsia/gfx_tests.cmx"
   }
 
   fuchsia_package_runner("ozone_demo_fuchsia") {