metrics: Deprecate "perf_data" in UMA proto

components/metrics/proto/chrome_user_metrics_extension.proto

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Protocol buffer for Chrome UMA (User Metrics Analysis).
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
@@ skipping 42 matching lines @@
 
   // Information about the user's browser and system configuration.
   optional SystemProfileProto system_profile = 3;
 
   // This message will log one or more of the following event types:
   repeated UserActionEventProto user_action_event = 4;
   repeated OmniboxEventProto omnibox_event = 5;
   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;
 
   // Additional data related with Cast-enabled devices.
   optional CastLogsProto cast_logs = 12;
 }