Update from https://crrev.com/308331

base/profiler/tracked_time.cc

 // 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.
 
 #include "base/profiler/tracked_time.h"
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <mmsystem.h>  // Declare timeGetTime()... after including build_config.
@@ skipping 28 matching lines @@
 // static
 Duration Duration::FromMilliseconds(int ms) { return Duration(ms); }
 
 int32 Duration::InMilliseconds() const { return ms_; }
 
 //------------------------------------------------------------------------------
 
 TrackedTime::TrackedTime() : ms_(0) {}
 TrackedTime::TrackedTime(int32 ms) : ms_(ms) {}
 TrackedTime::TrackedTime(const base::TimeTicks& time)
-    : ms_((time - base::TimeTicks()).InMilliseconds()) {
+    : ms_(static_cast<int32>((time - base::TimeTicks()).InMilliseconds())) {
 }
 
 // static
 TrackedTime TrackedTime::Now() {
 #if defined(OS_WIN)
   // Use lock-free accessor to 32 bit time.
   // Note that TimeTicks::Now() is built on this, so we have "compatible"
   // times when we down-convert a TimeTicks sample.
   return TrackedTime(base::TimeTicks::UnprotectedNow());
 #else
   // Posix has nice cheap 64 bit times, so we just down-convert it.
   return TrackedTime(base::TimeTicks::Now());
 #endif  // OS_WIN
 }
 
 Duration TrackedTime::operator-(const TrackedTime& other) const {
   return Duration(ms_ - other.ms_);
 }
 
 TrackedTime TrackedTime::operator+(const Duration& other) const {
   return TrackedTime(ms_ + other.ms_);
 }
 
 bool TrackedTime::is_null() const { return ms_ == 0; }
 
 }  // namespace tracked_objects