Add samples to BUILD.gn and their deps to DEPS

Also add missing GLFW DEPS entry

third_party/BUILD.gn

@@ -368,3 +368,56 @@ static_library("glfw") {
     ]
   }
 }
+
+###############################################################################
+# Header-only dependencies for samples
+###############################################################################
+
+if (dawn_standalone) {
+  # GLM
+  config("glm_public_config") {
+    include_dirs = [ "glm" ]
+  }
+  source_set("glm") {
+    public_configs = [ ":glm_public_config" ]
+    # GLM is header only but has too many files to list them.
+  }
+
+  # STB
+  config("stb_public_config") {
+    include_dirs = [ "stb" ]
+    cflags_cc = [ "-Wno-implicit-fallthrough" ]
+  }
+  source_set("stb") {
+    public_configs = [ ":stb_public_config" ]
+    sources = [
+      "stb/stb_image.h",
+    ]
+  }
+
+  # PicoJSON
+  config("picojson_public_config") {
+    include_dirs = [ "." ]
+  }
+  source_set("picojson") {
+    public_configs = [ ":picojson_public_config" ]
+    sources = [
+      "picojson/picojson.h",
+    ]
+  }
+
+  # Tiny glTF Loader
+  config("tiny_gltf_loader_public_config") {
+    include_dirs = [ "." ]
+  }
+  source_set("tiny_gltf_loader") {
+    public_configs = [ ":tiny_gltf_loader_public_config" ]
+    public_deps = [
+      ":picojson",
+      ":stb",
+    ]
+    sources = [
+      "tinygltfloader/tiny_gltf_loader.h",
+    ]
+  }
+}