Make code generated for histogram macros more compact.

base/metrics/histogram_base.h

Index: base/metrics/histogram_base.h
===================================================================
--- base/metrics/histogram_base.h	(revision 251312)
+++ base/metrics/histogram_base.h	(working copy)
@@ -12,6 +12,7 @@
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/strings/string_piece.h"
 #include "base/time/time.h"
 
 class Pickle;
@@ -48,8 +49,8 @@
 
 class BASE_EXPORT HistogramBase {
  public:
-  typedef int Sample;                   // Used for samples.
-  typedef subtle::Atomic32 AtomicCount; // Used to count samples.
+  typedef int Sample;                    // Used for samples.
+  typedef subtle::Atomic32 AtomicCount;  // Used to count samples.
   typedef int32 Count;  // Used to manipulate counts in temporaries.
 
   static const Sample kSampleType_MAX;  // INT_MAX
@@ -92,6 +93,11 @@
 
   std::string histogram_name() const { return histogram_name_; }
 
+  // Comapres |name| to the histogram name and triggers a DCHECK if they do not
+  // match. This is a helper function used by histogram macros, which results in
+  // in more compact machine code being generated by the macros.
+  void CheckName(const StringPiece& name) const;
+
   // Operations with Flags enum.
   int32 flags() const { return flags_; }
   void SetFlags(int32 flags);
@@ -137,7 +143,7 @@
   // customize the output.
   void WriteJSON(std::string* output) const;
 
-protected:
+ protected:
   // Subclasses should implement this function to make SerializeInfo work.
   virtual bool SerializeInfoImpl(Pickle* pickle) const = 0;