From a70aac6a11c4f9ccf417870b538ba50764556ca7 Mon Sep 17 00:00:00 2001
From: Doug Thayer <dothayer@mozilla.com>
Date: Wed, 9 Aug 2017 10:21:09 -0700
Subject: [PATCH] Bug 1388748 - Don't resize histogram ranges on init
 r=gfritzsche

We were using std::vector::assign, which resizes the vector to
match the incoming data. This isn't what we want, as ranges_ has
already been sized to bucket_count_ + 1. Instead, just use a
copy.

MozReview-Commit-ID: EGuW5jj7Rpq

--HG--
extra : rebase_source : 616d61fc27c7e43c22ea69e11e070ba958bf20a9
---
 ipc/chromium/src/base/histogram.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ipc/chromium/src/base/histogram.cc b/ipc/chromium/src/base/histogram.cc
index c8d0132fbe7f..97af3e5c90e7 100644
--- a/ipc/chromium/src/base/histogram.cc
+++ b/ipc/chromium/src/base/histogram.cc
@@ -273,7 +273,8 @@ Histogram::~Histogram() {
 }
 
 void Histogram::InitializeBucketRangeFromData(const int* buckets) {
-  ranges_.assign(buckets, buckets + bucket_count());
+  DCHECK_EQ(bucket_count_ + 1, ranges_.size());
+  std::copy_n(buckets, bucket_count_, ranges_.data());
   ResetRangeChecksum();
   DCHECK(ValidateBucketRanges());
 }