Add Read/WriteSizeT() functions to the pickle layer, plus one consumer.

base/metrics/histogram.cc

Index: base/metrics/histogram.cc
diff --git a/base/metrics/histogram.cc b/base/metrics/histogram.cc
index 6e30892179a7c83d60b7188d1393fba3c7c1b226..dcf771784f5aca2b391aea035b0774f7fb92deb4 100644
--- a/base/metrics/histogram.cc
+++ b/base/metrics/histogram.cc
@@ -37,13 +37,13 @@ bool ReadHistogramArguments(PickleIterator* iter,
                             int* flags,
                             int* declared_min,
                             int* declared_max,
-                            uint64* bucket_count,
+                            size_t* bucket_count,
                             uint32* range_checksum) {
   if (!iter->ReadString(histogram_name) ||
       !iter->ReadInt(flags) ||
       !iter->ReadInt(declared_min) ||
       !iter->ReadInt(declared_max) ||
-      !iter->ReadUInt64(bucket_count) ||
+      !iter->ReadSizeT(bucket_count) ||
       !iter->ReadUInt32(range_checksum)) {
     DLOG(ERROR) << "Pickle error decoding Histogram: " << *histogram_name;
     return false;
@@ -296,7 +296,7 @@ bool Histogram::SerializeInfoImpl(Pickle* pickle) const {
       pickle->WriteInt(flags()) &&
       pickle->WriteInt(declared_min()) &&
       pickle->WriteInt(declared_max()) &&
-      pickle->WriteUInt64(bucket_count()) &&
+      pickle->WriteSizeT(bucket_count()) &&
       pickle->WriteUInt32(bucket_ranges()->checksum());
 }
 
@@ -346,7 +346,7 @@ HistogramBase* Histogram::DeserializeInfoImpl(PickleIterator* iter) {
   int flags;
   int declared_min;
   int declared_max;
-  uint64 bucket_count;
+  size_t bucket_count;
   uint32 range_checksum;
 
   if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
@@ -634,7 +634,7 @@ HistogramBase* LinearHistogram::DeserializeInfoImpl(PickleIterator* iter) {
   int flags;
   int declared_min;
   int declared_max;
-  uint64 bucket_count;
+  size_t bucket_count;
   uint32 range_checksum;
 
   if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
@@ -689,7 +689,7 @@ HistogramBase* BooleanHistogram::DeserializeInfoImpl(PickleIterator* iter) {
   int flags;
   int declared_min;
   int declared_max;
-  uint64 bucket_count;
+  size_t bucket_count;
   uint32 range_checksum;
 
   if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
@@ -784,7 +784,7 @@ HistogramBase* CustomHistogram::DeserializeInfoImpl(PickleIterator* iter) {
   int flags;
   int declared_min;
   int declared_max;
-  uint64 bucket_count;
+  size_t bucket_count;
   uint32 range_checksum;
 
   if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,