Report PPAPI plugin load error code to UMA.

base/native_library_mac.mm

Index: base/native_library_mac.mm
diff --git a/base/native_library_mac.mm b/base/native_library_mac.mm
index 6544fcaed99eaf644bd36da96bdd864e8bd39327..f8a6698eb84d5a6fd6984c3423d31d9c70fb7e76 100644
--- a/base/native_library_mac.mm
+++ b/base/native_library_mac.mm
@@ -4,6 +4,8 @@
 
 #include "base/native_library.h"
 
+#include <ostream>
+
 #include <dlfcn.h>
 #include <mach-o/getsect.h>
 
@@ -42,8 +44,9 @@ static NativeLibraryObjCStatus GetObjCStatusForImage(
 }
 
 // static
+// TODO(xhwang): Fill |error|. See http://crbug.com/353771
 NativeLibrary LoadNativeLibrary(const base::FilePath& library_path,
-                                std::string* error) {
+                                NativeLibraryLoadError* /* error */) {
   // dlopen() etc. open the file off disk.
   if (library_path.Extension() == "dylib" || !DirectoryExists(library_path)) {
     void* dylib = dlopen(library_path.value().c_str(), RTLD_LAZY);
@@ -122,4 +125,10 @@ string16 GetNativeLibraryName(const string16& name) {
   return name + ASCIIToUTF16(".dylib");
 }
 
+// static
+std::ostream& operator<<(std::ostream& out,
+                         const NativeLibraryLoadError& error) {
+  return out << error.message;
+}
+
 }  // namespace base