Start work on GN build for content/common

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 22c9aa1020dbfeba2137c09e33cddaec850765f0..6199035e045c13d0b0ca2442f0491d2550ecb666 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",
@@ -59,6 +60,7 @@ group("root") {
     "//third_party/zlib",
     "//third_party:jpeg",
     "//tools/gn",
+    "//ui/accessibility",
     "//ui/base:ui_base",
     "//ui/events",
     "//ui/gfx",
@@ -84,11 +86,13 @@ group("root") {
       #"//third_party/WebKit/Source/platform",
       "//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",
     ]
   }
 }