Get mojo_shell building inside chromium checkout.

mojo/common/BUILD.gn

Index: mojo/common/BUILD.gn
diff --git a/mojo/common/BUILD.gn b/mojo/common/BUILD.gn
index 80446980af906639ba2c1ff81abe4021b96e0512..8f5dfaa0a4a7d1e061411615eff13e633d336f31 100644
--- a/mojo/common/BUILD.gn
+++ b/mojo/common/BUILD.gn
@@ -18,6 +18,7 @@ component("common_base") {
   sources = [
     "common_type_converters.cc",
     "common_type_converters.h",
+    "data_pipe_file_utils.cc",
     "data_pipe_utils.cc",
     "data_pipe_utils.h",
     "handle_watcher.cc",
@@ -27,6 +28,8 @@ component("common_base") {
     "message_pump_mojo_handler.h",
     "time_helper.cc",
     "time_helper.h",
+    "weak_binding_set.h",
+    "weak_interface_ptr_set.h",
   ]
 
   defines = [ "MOJO_COMMON_IMPLEMENTATION" ]
@@ -76,3 +79,21 @@ test("mojo_common_unittests") {
     "message_pump_mojo_unittest.cc",
   ]
 }
+
+if (!is_component_build) {
+  source_set("tracing_impl") {
+    sources = [
+      "trace_controller_impl.cc",
+      "trace_controller_impl.h",
+      "tracing_impl.cc",
+      "tracing_impl.h",
+    ]
+
+    deps = [
+      "//base",
+      "//third_party/mojo/src/mojo/public/cpp/application",
+      "//third_party/mojo/src/mojo/public/cpp/bindings",
+      "//mojo/services/tracing:bindings",
+    ]
+  }
+}