Add Pickle::Read/WriteUint64.

base/pickle.h

Index: base/pickle.h
===================================================================
--- base/pickle.h	(revision 29613)
+++ base/pickle.h	(working copy)
@@ -70,6 +70,7 @@
   bool ReadSize(void** iter, size_t* result) const;
   bool ReadUInt32(void** iter, uint32* result) const;
   bool ReadInt64(void** iter, int64* result) const;
+  bool ReadUInt64(void** iter, uint64* result) const;
   bool ReadIntPtr(void** iter, intptr_t* result) const;
   bool ReadString(void** iter, std::string* result) const;
   bool ReadWString(void** iter, std::wstring* result) const;
@@ -103,6 +104,9 @@
   bool WriteInt64(int64 value) {
     return WriteBytes(&value, sizeof(value));
   }
+  bool WriteUInt64(uint64 value) {
+    return WriteBytes(&value, sizeof(value));
+  }
   bool WriteIntPtr(intptr_t value) {
     return WriteBytes(&value, sizeof(value));
   }