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

base/pickle.cc

Index: base/pickle.cc
diff --git a/base/pickle.cc b/base/pickle.cc
index 2d7a051b20077e20d86346867f414cb3ab961ea6..a0933fb7b91ce469f403225614afca3db6384c6e 100644
--- a/base/pickle.cc
+++ b/base/pickle.cc
@@ -106,6 +106,15 @@ bool PickleIterator::ReadUInt64(uint64* result) {
   return ReadBuiltinType(result);
 }
 
+bool PickleIterator::ReadSizeT(size_t* result) {
+  // Always read size_t as a 64-bit value to ensure compatibility between 32-bit
+  // and 64-bit processes.
+  uint64 result_uint64 = 0;
+  bool success = ReadBuiltinType(&result_uint64);
+  *result = static_cast<size_t>(result_uint64);

[Tom Sepez, 2014/10/01 19:12:45]

I'd be OK with this so long as we did a check that result_uint64 <
std::numeric_limits<size_t>::max, returning false if it isnt.  In that case,
when you are sending too big a value from 64 to 32, we fail hard.

[Peter Kasting, 2014/10/01 19:42:08]

Sure.  Changed static_cast to checked_cast to achieve this.

+  return success;
+}
+
 bool PickleIterator::ReadFloat(float* result) {
   // crbug.com/315213
   // The source data may not be properly aligned, and unaligned float reads