Report PPAPI plugin load error code to UMA.

mojo/examples/pepper_container_app/plugin_module.cc

 // Copyright 2014 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 "mojo/examples/pepper_container_app/plugin_module.h"
 
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
@@ skipping 51 matching lines @@
 #if defined(OS_WIN)
   static const wchar_t plugin_name[] = L"ppapi_example_gles2_spinning_cube.dll";
 #elif defined(OS_MACOSX)
   static const char plugin_name[] = "ppapi_example_gles2_spinning_cube.plugin";
 #elif defined(OS_POSIX)
   static const char plugin_name[] = "libppapi_example_gles2_spinning_cube.so";
 #endif
 
   base::FilePath plugin_path(plugin_name);
 
-  std::string error;
-  plugin_module_.Reset(
-      base::LoadNativeLibrary(plugin_path, &error));
+  base::NativeLibraryLoadError error;
+  plugin_module_.Reset(base::LoadNativeLibrary(plugin_path, &error));
 
   if (!plugin_module_.is_valid()) {
     LOG(WARNING) << "Cannot load " << plugin_path.AsUTF8Unsafe()
-                 << ". Error: " << error;
+                 << ". Error: " << error.ToString();
     return;
   }
 
   entry_points_.get_interface =
       reinterpret_cast<PP_GetInterface_Func>(
           plugin_module_.GetFunctionPointer("PPP_GetInterface"));
   if (!entry_points_.get_interface) {
     LOG(WARNING) << "No PPP_GetInterface in plugin library";
     return;
   }
@@ skipping 13 matching lines @@
           plugin_module_.GetFunctionPointer("PPP_ShutdownModule"));
 
   int32_t result = entry_points_.initialize_module(pp_module(),
                                                    &GetInterface);
   if (result != PP_OK)
     LOG(WARNING) << "Initializing module failed with error " << result;
 }
 
 }  // namespace examples
 }  // namespace mojo