Make sure that ScratchBuffer::Allocate() always return 8-byte aligned address.

mojo/public/cpp/bindings/lib/scratch_buffer.cc

Index: mojo/public/cpp/bindings/lib/scratch_buffer.cc
diff --git a/mojo/public/cpp/bindings/lib/scratch_buffer.cc b/mojo/public/cpp/bindings/lib/scratch_buffer.cc
index 9d23dcb13bba25b7b2dde5d1d5d5fc4f56847ca7..dee048f3a1ac3078fe0f564207e9d68bfe7b9d14 100644
--- a/mojo/public/cpp/bindings/lib/scratch_buffer.cc
+++ b/mojo/public/cpp/bindings/lib/scratch_buffer.cc
@@ -80,11 +80,12 @@ bool ScratchBuffer::AddOverflowSegment(size_t delta) {
     return false;
 
   // Ensure segment buffer is aligned.
-  size_t segment_size = internal::Align(sizeof(Segment)) + delta;
-  Segment* segment = static_cast<Segment*>(malloc(segment_size));
+  size_t padded_segment_size = internal::Align(sizeof(Segment));
+  Segment* segment = static_cast<Segment*>(
+      malloc(padded_segment_size + delta));
   if (segment) {
     segment->next = overflow_;
-    segment->cursor = reinterpret_cast<char*>(segment + 1);
+    segment->cursor = reinterpret_cast<char*>(segment) + padded_segment_size;

[darin (slow to review), 2014/05/05 22:55:52]

good catch!

     segment->end = segment->cursor + delta;
     overflow_ = segment;
     return true;