Handle EAGAIN error for the mincore syscall used

base/trace_event/process_memory_dump.h

 // Copyright 2015 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_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_
 #define BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_
 
 #include <vector>
 
 #include "base/base_export.h"
@@ skipping 30 matching lines @@
     int importance;
     const char* type;
   };
 
   // Maps allocator dumps absolute names (allocator_name/heap/subheap) to
   // MemoryAllocatorDump instances.
   using AllocatorDumpsMap =
       SmallMap<hash_map<std::string, MemoryAllocatorDump*>>;
 
 #if defined(COUNT_RESIDENT_BYTES_SUPPORTED)
-  // Returns the total bytes resident for a virtual address range, with given
-  // |start_address| and |mapped_size|. |mapped_size| is specified in bytes. The
-  // value returned is valid only if the given range is currently mmapped by the
-  // process. The |start_address| must be page-aligned.
-  static size_t CountResidentBytes(void* start_address, size_t mapped_size);
+  // Counts the total bytes resident for a virtual address range, with given
+  // |start_address| and |mapped_size| and sets |resident_size|. |mapped_size|
+  // is specified in bytes. The value returned is valid only if the given range
+  // is currently mmapped by the process. The |start_address| must be
+  // page-aligned.
+  // Returns true on success.
+  static bool CountResidentBytes(void* start_address,
+                                 size_t mapped_size,
+                                 size_t* resident_size);
 #endif
 
   ProcessMemoryDump(const scoped_refptr<MemoryDumpSessionState>& session_state);
   ~ProcessMemoryDump();
 
   // Creates a new MemoryAllocatorDump with the given name and returns the
   // empty object back to the caller.
   // Arguments:
   //   absolute_name: a name that uniquely identifies allocator dumps produced
   //       by this provider. It is possible to specify nesting by using a
@@ skipping 99 matching lines @@
   // Keeps track of relationships between MemoryAllocatorDump(s).
   std::vector<MemoryAllocatorDumpEdge> allocator_dumps_edges_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessMemoryDump);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_