base: Add debugging to track down CreateFileMapping() errors.

base/memory/shared_memory_win.cc

Index: base/memory/shared_memory_win.cc
diff --git a/base/memory/shared_memory_win.cc b/base/memory/shared_memory_win.cc
index 7de87a98a9dd91a3647c4c20c47e8c977136e9c9..6623e8caefde4b74157be1723414706418374f0f 100644
--- a/base/memory/shared_memory_win.cc
+++ b/base/memory/shared_memory_win.cc
@@ -8,6 +8,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "base/debug/alias.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/rand_util.h"
@@ -108,6 +110,11 @@ HANDLE CreateFileMappingWithReducedPermissions(SECURITY_ATTRIBUTES* sa,
   HANDLE h = CreateFileMapping(INVALID_HANDLE_VALUE, sa, PAGE_READWRITE, 0,
                                static_cast<DWORD>(rounded_size), name);
   if (!h) {
+    // Debugging to help track down https://crbug.com/585013
+    DWORD last_error = ::GetLastError();
+    base::debug::Alias(&last_error);
+    base::debug::DumpWithoutCrashing();

[Nico, 2016/05/24 00:22:13]

is this code perf-sensitive? Should this just be full-on crash?

[erikchen, 2016/05/24 00:41:20]

This is perf-sensitive, but shouldn't be hit often. I don't want a full-on crash
because that would take down the browser process, whereas now the bug just takes
down the renderer process.

+
     LogError(CREATE_FILE_MAPPING_FAILURE);
     return nullptr;
   }