Have ScratchBuffer::Allocate prefer allocating on the stack even if a previous

mojo/public/bindings/lib/buffer.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/public/bindings/lib/buffer.h"
 
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ skipping 16 matching lines @@
   while (overflow_) {
     Segment* doomed = overflow_;
     overflow_ = overflow_->next;
     free(doomed);
   }
 }
 
 void* ScratchBuffer::Allocate(size_t delta) {
   delta = internal::Align(delta);
 
-  void* result =
-      AllocateInSegment((overflow_ != NULL) ? overflow_ : &fixed_, delta);
+  void* result = AllocateInSegment(&fixed_, delta);
   if (result)
     return result;
 
+  if (overflow_) {
+    result = AllocateInSegment(overflow_, delta);
+    if (result)
+      return result;
+  }
+
   AddOverflowSegment(delta);
-  return Allocate(delta);
+  return AllocateInSegment(overflow_, delta);
 }
 
 void* ScratchBuffer::AllocateInSegment(Segment* segment, size_t delta) {
   void* result;
   if (static_cast<size_t>(segment->end - segment->cursor) >= delta) {
     result = segment->cursor;
     memset(result, 0, delta);
     segment->cursor += delta;
   } else {
     result = NULL;
@@ skipping 46 matching lines @@
 
 void* FixedBuffer::Leak() {
   char* ptr = ptr_;
   ptr_ = NULL;
   cursor_ = 0;
   size_ = 0;
   return ptr;
 }
 
 }  // namespace mojo