Serialize/Deserialize support in HistogramBase

base/metrics/histogram_base.h

Index: base/metrics/histogram_base.h
diff --git a/base/metrics/histogram_base.h b/base/metrics/histogram_base.h
index 302795a73fc7a4072bb4fc26ccb86461a5f790c0..5a9d413f76401df515d9f9860850782934ac5f36 100644
--- a/base/metrics/histogram_base.h
+++ b/base/metrics/histogram_base.h
@@ -11,6 +11,9 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 
+class Pickle;
+class PickleIterator;
+
 namespace base {
 
 class DictionaryValue;
@@ -59,6 +62,10 @@ class BASE_EXPORT HistogramBase {
   HistogramBase(const std::string& name);
   virtual ~HistogramBase();
 
+  // Create or find existing histogram that matches the pickled info. Returns
+  // NULL if the pickled data has problems.
+  static HistogramBase* DeserializeHistogramInfo(PickleIterator* iter);
+
   std::string histogram_name() const { return histogram_name_; }
 
   // Operations with Flags enum.
@@ -69,14 +76,22 @@ class BASE_EXPORT HistogramBase {
   virtual HistogramType GetHistogramType() const = 0;
 
   // Whether the histogram has construction arguments as parameters specified.
-  // For histograms that don't have the concept of minimum, maximum or
-  // bucket_count, this function always returns false.
+  // For histograms that don't have the concept of |minimum|, |maximum| or
+  // |bucket_count|, this function always returns false.
   virtual bool HasConstructionArguments(Sample minimum,
                                         Sample maximum,
                                         size_t bucket_count) const = 0;
 
   virtual void Add(Sample value) = 0;
 
+  virtual void AddSamples(const HistogramSamples& samples) = 0;
+  virtual bool AddSamplesFromPickle(PickleIterator* iter) = 0;
+
+  // Serialize the histogram info into |pickle|.
+  // Note. This only serialize construction info of the histogram, but not
+  // serialize the samples.

[Ilya Sherman, 2012/12/29 00:17:30]

nit: "Note: This only serializes the construction parameters for the histogram;
it does not serialize the samples."

[kaiwang, 2013/01/08 00:51:40]

Done.

+  bool SerializeInfo(Pickle* pickle) const;
+
   // Snapshot the current complete set of sample data.
   // Override with atomic/locked snapshot if needed.
   virtual scoped_ptr<HistogramSamples> SnapshotSamples() const = 0;
@@ -91,6 +106,9 @@ class BASE_EXPORT HistogramBase {
   void WriteJSON(std::string* output) const;
 
 protected:
+  // Subclasses should implement this function to make SerializeInfo work.
+  virtual bool SerializeInfoImpl(Pickle* pickle) const = 0;
+
   // Writes information about the construction parameters in |params|.
   virtual void GetParameters(DictionaryValue* params) const = 0;