Start work on GN build for content/common

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 4b392ac7f7f6821d6d5f396f67aefe0822326e4e..3be2e29c5c34d68329e3a997f6008dea1c676d8f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -26,6 +26,7 @@ group("root") {
     "//components/os_crypt",
     "//components/startup_metric_utils",
     "//components/resources:components_resources",
+    "//components/tracing",
     "//components/translate:translate_core_browser",
     "//components/translate:translate_core_common",
     "//components/url_matcher",
@@ -57,6 +58,7 @@ group("root") {
     "//third_party/zlib",
     "//third_party:jpeg",
     "//tools/gn",
+    "//ui/accessibility",
     "//ui/base:ui_base",
     "//ui/events",
     "//ui/gfx",
@@ -82,11 +84,13 @@ group("root") {
       "//third_party/libusb",
       "//third_party/WebKit/Source/wtf",  # TODO(brettw) re-enable for Android.
       "//tools/gn",
+
+      # This UI stuff is blocked on Skia.
+      "//ui/accessibility",
       "//ui/base:ui_base",
       "//ui/events",
       "//ui/gfx",
-      "//ui/surface",  # TODO(brettw): Skia does not build on Android yet.
-                       # Re-enable this when skia is fixed.
+      "//ui/surface",
     ]
   }
 }