GN: Refactor modules_unittests to eliminate package boundary violations.

webrtc/modules/media_file/BUILD.gn

Index: webrtc/modules/media_file/BUILD.gn
diff --git a/webrtc/modules/media_file/BUILD.gn b/webrtc/modules/media_file/BUILD.gn
index f4e93c9034909ed87ec358b2aa4032ca1785b325..8003cd8160f0425e6b5c7fe2e3e671a7247020f5 100644
--- a/webrtc/modules/media_file/BUILD.gn
+++ b/webrtc/modules/media_file/BUILD.gn
@@ -39,3 +39,27 @@ rtc_static_library("media_file") {
     "../../system_wrappers",
   ]
 }
+
+if (rtc_include_tests) {
+  rtc_source_set("media_file_unittests") {
+    testonly = true
+    sources = [
+      "media_file_unittest.cc",
+    ]
+    deps = [
+      ":media_file",
+      "../../system_wrappers:system_wrappers",
+      "../../test:test_support",
+    ]
+    if (is_win) {
+      cflags = [
+        # TODO(kjellander): bugs.webrtc.org/261: Fix this warning.
+        "/wd4373",  # virtual function override.
+      ]
+    }
+    if (!build_with_chromium && is_clang) {
+      # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+      suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
+    }
+  }
+}