GN: Make content_shell and webkit_unit_tests work in component build

content/common/BUILD.gn

Index: content/common/BUILD.gn
diff --git a/content/common/BUILD.gn b/content/common/BUILD.gn
index 02efe32b1767100280d005ee3771393953420393..0f2a380556682964999b3939965955c133c5747d 100644
--- a/content/common/BUILD.gn
+++ b/content/common/BUILD.gn
@@ -49,8 +49,6 @@ source_set("common") {
       "//cc",
       "//ipc",
       "//ipc/mojo",
-      "//mojo/environment:chromium",
-      "//mojo/system",
       # TODO: the dependency on gl_in_process_context should be decoupled from
       # content and moved to android_webview. See crbug.com/365797.
       "//gpu/command_buffer/client:gl_in_process_context",
@@ -61,7 +59,10 @@ source_set("common") {
       "//gpu/skia_bindings",
       "//media",
       "//media:shared_memory_support",
+      "//mojo/environment:chromium",
       "//mojo/public/interfaces/application",
+      "//mojo/system",
+      "//sandbox",
       "//third_party/WebKit/public:blink",
       "//ui/gl",
       "//webkit/browser:storage",