Fix for setting the os listed in metrics reporting for Blimp.

components/metrics/BUILD.gn

Index: components/metrics/BUILD.gn
diff --git a/components/metrics/BUILD.gn b/components/metrics/BUILD.gn
index ac17405f14af1b16c0b31f7bdbb90d7b8e64c2c4..9fac1a3cee3ebbcdeba70a73298718fff9b358b8 100644
--- a/components/metrics/BUILD.gn
+++ b/components/metrics/BUILD.gn
@@ -7,6 +7,12 @@ declare_args() {
   metrics_use_blimp = false
 }
 
+# These are only used by the blimp team, which has entirely migrated to gn,
+# so this logic is not replicated in the gyp file.
+if (metrics_use_blimp) {
+  defines = [ "OVERRIDE_OS_NAME_TO_BLIMP" ]
+}
+
 # GYP version: components/metrics.gypi:metrics
 source_set("metrics") {
   sources = [
@@ -366,10 +372,4 @@ source_set("unit_tests") {
   if (is_chromeos) {
     deps += [ ":leak_detector_unit_tests" ]
   }
-
-  # These are only used by the blimp team, which has entirely migrated to gn,
-  # so this logic is not replicated in the gyp file.
-  if (metrics_use_blimp) {
-    defines = [ "OVERRIDE_OS_NAME_TO_BLIMP" ]
-  }
 }