Move part of metrics from chrome/common to components

chrome/common/metrics/proto/histogram_event.proto

-// Copyright (c) 2012 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.
-//
-// Histogram-collected metrics.
-
-syntax = "proto2";
-
-option optimize_for = LITE_RUNTIME;
-
-package metrics;
-
-// Next tag: 4
-message HistogramEventProto {
-  // The name of the histogram, hashed.
-  optional fixed64 name_hash = 1;
-
-  // The sum of all the sample values.
-  // Together with the total count of the sample values, this allows us to
-  // compute the average value.  The count of all sample values is just the sum
-  // of the counts of all the buckets.
-  optional int64 sum = 2;
-
-  // The per-bucket data.
-  message Bucket {
-    // Each bucket's range is bounded by min <= x < max.
-    // It is valid to omit one of these two fields in a bucket, but not both.
-    // If the min field is omitted, its value is assumed to be equal to max - 1.
-    // If the max field is omitted, its value is assumed to be equal to the next
-    // bucket's min value (possibly computed per above).  The last bucket in a
-    // histogram should always include the max field.
-    optional int64 min = 1;
-    optional int64 max = 2;
-
-    // The bucket's index in the list of buckets, sorted in ascending order.
-    // This field was intended to provide extra redundancy to detect corrupted
-    // records, but was never used.  As of M31, it is no longer sent by Chrome
-    // clients to reduce the UMA upload size.
-    optional int32 bucket_index = 3 [deprecated = true];
-
-    // The number of entries in this bucket.
-    optional int64 count = 4;
-  }
-  repeated Bucket bucket = 3;
-}