Remove std::string histogram name from HistogramBase object.

base/metrics/histogram.h

Index: base/metrics/histogram.h
diff --git a/base/metrics/histogram.h b/base/metrics/histogram.h
index 6e5821d4680fd5d57dcfcbf4065d9a9a841b5e4d..47bffef695f14c62f51cda61d112c3d349b2995f 100644
--- a/base/metrics/histogram.h
+++ b/base/metrics/histogram.h
@@ -140,7 +140,7 @@ class BASE_EXPORT Histogram : public HistogramBase {
 
   // Create a histogram using data in persistent storage.
   static std::unique_ptr<HistogramBase> PersistentCreate(
-      const std::string& name,
+      const char* name,
       Sample minimum,
       Sample maximum,
       const BucketRanges* ranges,
@@ -217,7 +217,7 @@ class BASE_EXPORT Histogram : public HistogramBase {
 
   // |ranges| should contain the underflow and overflow buckets. See top
   // comments for example.
-  Histogram(const std::string& name,
+  Histogram(const char* name,
             Sample minimum,
             Sample maximum,
             const BucketRanges* ranges);
@@ -228,7 +228,7 @@ class BASE_EXPORT Histogram : public HistogramBase {
   // the life of this memory is managed externally and exceeds the lifetime
   // of this object. Practically, this memory is never released until the
   // process exits and the OS cleans it up.
-  Histogram(const std::string& name,
+  Histogram(const char* name,
             Sample minimum,
             Sample maximum,
             const BucketRanges* ranges,
@@ -357,7 +357,7 @@ class BASE_EXPORT LinearHistogram : public Histogram {
 
   // Create a histogram using data in persistent storage.
   static std::unique_ptr<HistogramBase> PersistentCreate(
-      const std::string& name,
+      const char* name,
       Sample minimum,
       Sample maximum,
       const BucketRanges* ranges,
@@ -394,12 +394,12 @@ class BASE_EXPORT LinearHistogram : public Histogram {
  protected:
   class Factory;
 
-  LinearHistogram(const std::string& name,
+  LinearHistogram(const char* name,
                   Sample minimum,
                   Sample maximum,
                   const BucketRanges* ranges);
 
-  LinearHistogram(const std::string& name,
+  LinearHistogram(const char* name,
                   Sample minimum,
                   Sample maximum,
                   const BucketRanges* ranges,
@@ -446,7 +446,7 @@ class BASE_EXPORT BooleanHistogram : public LinearHistogram {
 
   // Create a histogram using data in persistent storage.
   static std::unique_ptr<HistogramBase> PersistentCreate(
-      const std::string& name,
+      const char* name,
       const BucketRanges* ranges,
       const DelayedPersistentAllocation& counts,
       const DelayedPersistentAllocation& logged_counts,
@@ -459,8 +459,8 @@ class BASE_EXPORT BooleanHistogram : public LinearHistogram {
   class Factory;
 
  private:
-  BooleanHistogram(const std::string& name, const BucketRanges* ranges);
-  BooleanHistogram(const std::string& name,
+  BooleanHistogram(const char* name, const BucketRanges* ranges);
+  BooleanHistogram(const char* name,
                    const BucketRanges* ranges,
                    const DelayedPersistentAllocation& counts,
                    const DelayedPersistentAllocation& logged_counts,
@@ -496,7 +496,7 @@ class BASE_EXPORT CustomHistogram : public Histogram {
 
   // Create a histogram using data in persistent storage.
   static std::unique_ptr<HistogramBase> PersistentCreate(
-      const std::string& name,
+      const char* name,
       const BucketRanges* ranges,
       const DelayedPersistentAllocation& counts,
       const DelayedPersistentAllocation& logged_counts,
@@ -517,10 +517,9 @@ class BASE_EXPORT CustomHistogram : public Histogram {
  protected:
   class Factory;
 
-  CustomHistogram(const std::string& name,
-                  const BucketRanges* ranges);
+  CustomHistogram(const char* name, const BucketRanges* ranges);
 
-  CustomHistogram(const std::string& name,
+  CustomHistogram(const char* name,
                   const BucketRanges* ranges,
                   const DelayedPersistentAllocation& counts,
                   const DelayedPersistentAllocation& logged_counts,