Support moving pending requests from one DataUseRecorder to another

components/data_use_measurement/core/data_use.cc

Index: components/data_use_measurement/core/data_use.cc
diff --git a/components/data_use_measurement/core/data_use.cc b/components/data_use_measurement/core/data_use.cc
index 9c34e8a8ce2faf750ca0624e44df7db2576a1699..8750f45e2bf4c5e001c0eb8ecacad2ff4fbc4f65 100644
--- a/components/data_use_measurement/core/data_use.cc
+++ b/components/data_use_measurement/core/data_use.cc
@@ -16,15 +16,8 @@ DataUse::~DataUse() {}
 void DataUse::IncrementTotalBytes(int64_t bytes_received, int64_t bytes_sent) {
   total_bytes_received_ += bytes_received;
   total_bytes_sent_ += bytes_sent;
-}
-
-void DataUse::MergeFrom(const DataUse& other) {
-  // Traffic type need not be same while merging. One of the data use created
-  // when mainframe is created could have UNKNOWN traffic type, and later merged
-  // with the data use created for its mainframe request which could be
-  // USER_TRAFFIC.
-  total_bytes_sent_ += other.total_bytes_sent_;
-  total_bytes_received_ += other.total_bytes_received_;
+  DCHECK_LE(0, total_bytes_received_);
+  DCHECK_LE(0, total_bytes_sent_);
 }
 
 }  // namespace data_use_measurement