linux: don't always print dlopen errors from LoadNativeLibrary

base/native_library.h

 // Copyright (c) 2011 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_NATIVE_LIBRARY_H_
 #define BASE_NATIVE_LIBRARY_H_
 #pragma once
 
 // This file defines a cross-platform "NativeLibrary" type which represents
 // a loadable module.
@@ skipping 34 matching lines @@
     CFBundleRef bundle;
     void* dylib;
   };
 };
 typedef NativeLibraryStruct* NativeLibrary;
 #elif defined(OS_POSIX)
 typedef void* NativeLibrary;
 #endif  // OS_*
 
 // Loads a native library from disk.  Release it with UnloadNativeLibrary when
-// you're done.
-BASE_API NativeLibrary LoadNativeLibrary(const FilePath& library_path);
+// you're done.  Returns NULL on failure.
+// If |err| is not NULL, it may be filled in with an error message on
+// error.
+BASE_API NativeLibrary LoadNativeLibrary(const FilePath& library_path,
+                                         std::string* error);
 
 #if defined(OS_WIN)
 // Loads a native library from disk.  Release it with UnloadNativeLibrary when
 // you're done.
 // This function retrieves the LoadLibrary function exported from kernel32.dll
 // and calls it instead of directly calling the LoadLibrary function via the
 // import table.
 BASE_API NativeLibrary LoadNativeLibraryDynamically(
     const FilePath& library_path);
 #endif  // OS_WIN
 
 // Unloads a native library.
 BASE_API void UnloadNativeLibrary(NativeLibrary library);
 
 // Gets a function pointer from a native library.
 BASE_API void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
                                                    const char* name);
 
 // Returns the full platform specific name for a native library.
 // For example:
 // "mylib" returns "mylib.dll" on Windows, "libmylib.so" on Linux,
 // "mylib.dylib" on Mac.
 BASE_API string16 GetNativeLibraryName(const string16& name);
 
 }  // namespace base
 
 #endif  // BASE_NATIVE_LIBRARY_H_