Fix build breakage at r30320.

base/pickle.cc

 // Copyright (c) 2006-2008 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 "base/pickle.h"
 
 #include <stdlib.h>
 
 #include <algorithm>  // for max()
 #include <limits>
@@ skipping 351 matching lines @@
   variable_buffer_offset_ =
       data_ptr - reinterpret_cast<char*>(header_) - sizeof(int);
 
   // EndWrite doesn't necessarily have to be called after the write operation,
   // so we call it here to pad out what the caller will eventually write.
   EndWrite(data_ptr, length);
   return data_ptr;
 }
 
 void Pickle::TrimWriteData(int new_length) {
-  DCHECK_NE(variable_buffer_offset_, 0);
+  DCHECK_NE(variable_buffer_offset_, 0U);
 
   // Fetch the the variable buffer size
   int* cur_length = reinterpret_cast<int*>(
       reinterpret_cast<char*>(header_) + variable_buffer_offset_);
 
   if (new_length < 0 || new_length > *cur_length) {
     NOTREACHED() << "Invalid length in TrimWriteData.";
     return;
   }
 
@@ skipping 23 matching lines @@
   DCHECK(header_size <= static_cast<size_t>(kPayloadUnit));
 
   const Header* hdr = reinterpret_cast<const Header*>(start);
   const char* payload_base = start + header_size;
   const char* payload_end = payload_base + hdr->payload_size;
   if (payload_end < payload_base)
     return NULL;
 
   return (payload_end > end) ? NULL : payload_end;
 }