metrics: Deprecate "perf_data" in UMA proto

components/metrics/proto/chrome_user_metrics_extension.proto

Index: components/metrics/proto/chrome_user_metrics_extension.proto
diff --git a/components/metrics/proto/chrome_user_metrics_extension.proto b/components/metrics/proto/chrome_user_metrics_extension.proto
index cf52be233a561a1ef2a40fdfe270ed79b2fe3fbf..42f8c156f4574d64bc7b3f80cce5cd01e1856850 100644
--- a/components/metrics/proto/chrome_user_metrics_extension.proto
+++ b/components/metrics/proto/chrome_user_metrics_extension.proto
@@ -60,8 +60,8 @@ message ChromeUserMetricsExtension {
   repeated HistogramEventProto histogram_event = 6;
   repeated ProfilerEventProto profiler_event = 7;
 
-  // TODO(sque): Deprecate this field and use |sampled_profile| instead.
-  repeated PerfDataProto perf_data = 8;
+  // This field is no longer used. Use |sampled_profile| instead.
+  repeated PerfDataProto perf_data = 8 [deprecated=true];
 
   // A list of all collected sample-based profiles since the last UMA upload.
   repeated SampledProfile sampled_profile = 11;