Add crash keys about field trial shared memory errors.

base/memory/shared_memory_helper.h

 // Copyright 2016 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.
 
 #ifndef BASE_MEMORY_SHARED_MEMORY_HELPER_H_
 #define BASE_MEMORY_SHARED_MEMORY_HELPER_H_
 
 #include "base/memory/shared_memory.h"
 
 #include <fcntl.h>
 
 namespace base {
 
 #if !defined(OS_ANDROID)
 // Makes a temporary file, fdopens it, and then unlinks it. |fp| is populated
 // with the fdopened FILE. |readonly_fd| is populated with the opened fd if
 // options.share_read_only is true. |path| is populated with the location of
 // the file before it was unlinked.
-// Returns false if there's an unhandled failure.
+// Returns false if there's a failure and sets |error|.
 bool CreateAnonymousSharedMemory(const SharedMemoryCreateOptions& options,
                                  ScopedFILE* fp,
                                  ScopedFD* readonly_fd,
-                                 FilePath* path);
+                                 FilePath* path,
+                                 SharedMemoryError* error);
 
 // Takes the outputs of CreateAnonymousSharedMemory and maps them properly to
 // |mapped_file| or |readonly_mapped_file|, depending on which one is populated.
-bool PrepareMapFile(ScopedFILE fp, ScopedFD readonly_fd, int* mapped_file,
-                    int* readonly_mapped_file);
+// Returns false if there's a failure and sets |error|.
+bool PrepareMapFile(ScopedFILE fp,
+                    ScopedFD readonly_fd,
+                    int* mapped_file,
+                    int* readonly_mapped_file,
+                    SharedMemoryError* error);
 #endif
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_SHARED_MEMORY_HELPER_H_