platform2: Add libmetrics slotted library targets.

BUG=chromium:342866
CQ-DEPEND=CL:185187
CQ-DEPEND=CL:186026
TEST=Trybot run on paladin, release, and chromiumos-sdk builders.

Change-Id: I6d6d2c16c91640774988995aecc93226eda3d353
Reviewed-on: https://chromium-review.googlesource.com/186037
Reviewed-by: Mike Frysinger <[email protected]>
Tested-by: Ben Chan <[email protected]>
Commit-Queue: Ben Chan <[email protected]>
diff --git a/platform.gyp b/platform.gyp
index a95d39a..a6522a1 100644
--- a/platform.gyp
+++ b/platform.gyp
@@ -8,6 +8,8 @@
       'dependencies': [
         '<(DEPTH)/libchromeos/libchromeos-180609.gyp:*',
         '<(DEPTH)/libchromeos/libchromeos-242728.gyp:*',
+        '<(DEPTH)/metrics/libmetrics-180609.gyp:*',
+        '<(DEPTH)/metrics/libmetrics-242728.gyp:*',
         '<(DEPTH)/metrics/metrics.gyp:*',
         '<(DEPTH)/power_manager/power_manager.gyp:*',
         '<(DEPTH)/system_api/system_api.gyp:*',