Turning return by const value to return by const ref in BirthOnThread::location()

base/tracked_objects.h

 // 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.
 
 #ifndef BASE_TRACKED_OBJECTS_H_
 #define BASE_TRACKED_OBJECTS_H_
 
 #include <map>
 #include <set>
 #include <stack>
@@ skipping 182 matching lines @@
 namespace tracked_objects {
 
 //------------------------------------------------------------------------------
 // For a specific thread, and a specific birth place, the collection of all
 // death info (with tallies for each death thread, to prevent access conflicts).
 class ThreadData;
 class BASE_EXPORT BirthOnThread {
  public:
   BirthOnThread(const Location& location, const ThreadData& current);
 
-  const Location location() const { return location_; }
+  const Location& location() const { return location_; }
   const ThreadData* birth_thread() const { return birth_thread_; }
 
  private:
   // File/lineno of birth.  This defines the essence of the task, as the context
   // of the birth (construction) often tell what the item is for.  This field
   // is const, and hence safe to access from any thread.
   const Location location_;
 
   // The thread that records births into this object.  Only this thread is
   // allowed to update birth_count_ (which changes over time).
@@ skipping 590 matching lines @@
   ProcessDataSnapshot();
   ~ProcessDataSnapshot();
 
   PhasedProcessDataSnapshotMap phased_snapshots;
   base::ProcessId process_id;
 };
 
 }  // namespace tracked_objects
 
 #endif  // BASE_TRACKED_OBJECTS_H_