Eliminate build warnings in base/ for Android x64

base/debug/proc_maps_linux.cc

 // Copyright (c) 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 "base/debug/proc_maps_linux.h"
 
 #include <fcntl.h>
 
 #if defined(OS_LINUX)
 #include <inttypes.h>
 #endif
 
 #include "base/file_util.h"
 #include "base/strings/string_split.h"
 
 #if defined(OS_ANDROID)
 // Bionic's inttypes.h defines PRI/SCNxPTR as an unsigned long int, which
 // is incompatible with Bionic's stdint.h defining uintptr_t as a unsigned int:

[Mark Mentovai, 2014/03/03 14:25:35]

What does Bionic’s inttypes.h define PRI/SCNxPTR as in __LP64__, and what does
stdint.h define uintptr_t as?

At the very least, the comment is incorrect. But it’s also quite possible that
you don’t need this new __LP64__ case inside the #ifdef, and can just put
!defined(__LP64__) on line 16.

 // https://code.google.com/p/android/issues/detail?id=57218
 #undef SCNxPTR
+#ifdef __LP64__
+#define SCNxPTR "lx"
+#else
 #define SCNxPTR "x"
 #endif
+#endif
 
 namespace base {
 namespace debug {
 
 // Scans |proc_maps| starting from |pos| returning true if the gate VMA was
 // found, otherwise returns false.
 static bool ContainsGateVMA(std::string* proc_maps, size_t pos) {
 #if defined(ARCH_CPU_ARM_FAMILY)
   // The gate VMA on ARM kernels is the interrupt vectors page.
   return proc_maps->find(" [vectors]\n", pos) != std::string::npos;
@@ skipping 120 matching lines @@
     regions.push_back(region);
     regions.back().path.assign(line + path_index);
   }
 
   regions_out->swap(regions);
   return true;
 }
 
 }  // namespace debug
 }  // namespace base