Make base a static ibrary

base/metrics/BUILD.gn

Index: base/metrics/BUILD.gn
diff --git a/base/metrics/BUILD.gn b/base/metrics/BUILD.gn
index 6dd212f887eb9b5541298123c844d1447ac84501..4c95f5d8c714ffd25acfbcd881f68cbc2baf26c8 100644
--- a/base/metrics/BUILD.gn
+++ b/base/metrics/BUILD.gn
@@ -2,7 +2,20 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("metrics") {
+# TODO(phosek) bug 570839: If field_trial.cc is in a static library,
+# hacl_helper_nonsfi doesn't link properly on Linux in debug builds. The
+# reasons for this seem to involve obscure toolchain bugs. This should be fixed
+# and this target should be a static_library unconditionally.
+import("//build/config/nacl/config.gni")
+if (is_nacl_nonsfi) {
+  metrics_target_type = "source_set"
+} else {
+  metrics_target_type = "static_library"
+}
+
+# Should be static library, see documentation on //base:base for discussion.
+#static_library("metrics") {  # Should be this when above TODO is resolved.
+target(metrics_target_type, "metrics") {
   sources = [
     "bucket_ranges.cc",
     "bucket_ranges.h",