Use 64 bit shift when convert uint64_t to ByteVector

components/rappor/byte_vector_utils.cc

Index: components/rappor/byte_vector_utils.cc
diff --git a/components/rappor/byte_vector_utils.cc b/components/rappor/byte_vector_utils.cc
index 69abcd4dffd8e3c8cfb55061c8aa2cc58c61cedf..02120cc2fd4b30659bf127d3f55bf73d840d3c83 100644
--- a/components/rappor/byte_vector_utils.cc
+++ b/components/rappor/byte_vector_utils.cc
@@ -78,6 +78,17 @@ bool HMAC_DRBG_Update(const std::string& provided_data,
 
 }  // namespace
 
+void Uint64ToByteVector(uint64_t value, uint64_t size, ByteVector* output) {
+  DCHECK_LE(size, 8u);
+  DCHECK_EQ(size, output->size());
+  for (size_t i = 0; i < size; i++) {
+    // Get the value of the i-th smallest byte and copy it to the byte vector.
+    uint64_t shift = i * 8;

[brucedawson, 2015/04/29 18:21:51]

Why is shift a uint64_t? The legal values are from 0-63 so an int or unsigned is
more than sufficient.

+    uint64_t byte_mask = uint64_t(0xff) << shift;

[Alexei Svitkine (slow), 2015/04/29 15:01:07]

Our style guide prefers static_cast<uint64_t>().

[Steven Holte, 2015/04/29 18:18:56]

Done.

+    (*output)[i] = (value & byte_mask) >> shift;
+  }
+}
+
 ByteVector* ByteVectorAnd(const ByteVector& lhs, ByteVector* rhs) {
   DCHECK_EQ(lhs.size(), rhs->size());
   for (size_t i = 0; i < lhs.size(); ++i) {