Update to build against libchrome-242728.

This CL updates metrics to build against libchrome-242728 and also converts
libmetrics into slotted libraries (libmetrics-180609 and libmetrics-242728).

BUG=chromium:341521
BUG=chromium:342866
CQ-DEPEND=CL:186027
CQ-DEPEND=CL:186026
CQ-DEPEND=CL:186037
CQ-DEPEND=CL:186092
CQ-DEPEND=CL:186028
CQ-DEPEND=CL:186029
CQ-DEPEND=CL:186038
CQ-DEPEND=CL:186093
CQ-DEPEND=CL:186100
CQ-DEPEND=CL:186039
TEST=Trybot run on paladin, release, and chromiumos-sdk builders.

Change-Id: I09dc3d47cfe24a22864abf217658c63493b35cba
Reviewed-on: https://chromium-review.googlesource.com/185187
Reviewed-by: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
diff --git a/metrics/libmetrics.gypi b/metrics/libmetrics.gypi
new file mode 100644
index 0000000..21af05d
--- /dev/null
+++ b/metrics/libmetrics.gypi
@@ -0,0 +1,29 @@
+{
+  'target_defaults': {
+    'dependencies': [
+      '../libchromeos/libchromeos-<(libbase_ver).gyp:libchromeos-<(libbase_ver)',
+    ],
+    'variables': {
+      'deps': [
+        'libchrome-<(libbase_ver)',
+      ]
+    },
+    'cflags_cc': [
+      '-fno-exceptions',
+    ],
+  },
+  'targets': [
+    {
+      'target_name': 'libmetrics-<(libbase_ver)',
+      'type': 'shared_library',
+      'cflags': [
+        '-fvisibility=default',
+      ],
+      'sources': [
+        'c_metrics_library.cc',
+        'metrics_library.cc',
+        'timer.cc',
+      ],
+    },
+  ],
+}