Report PPAPI plugin load error code to UMA.

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_
 
 // This file defines a cross-platform "NativeLibrary" type which represents
 // a loadable module.
 
@@ skipping 32 matching lines @@
   union {
     CFBundleRef bundle;
     void* dylib;
   };
 };
 typedef NativeLibraryStruct* NativeLibrary;
 #elif defined(OS_POSIX)
 typedef void* NativeLibrary;
 #endif  // OS_*
 
+#if defined(OS_WIN)
+typedef DWORD NativeLibraryLoadError;

[ddorwin, 2014/03/21 20:06:32]

While more explicit about what to expect, this forces the caller to ifdef its
code.
On the other hand, this is most often used for LOG statements, which happily
cast and work fine.

It seems like an odd thing to expose to all of Chromium (it's in base/). Also,
there is the issue of initialization. To address that, this could be a class
with a operator().

[xhwang, 2014/03/21 22:33:28]

I fixed the initialization issue with a struct. Most callers don't need to care
about ifdef. ppapi_thread.cc is the only exception because UMA doesn't support
string very well.

+#else
+typedef std::string NativeLibraryLoadError;
+#endif  // OS_WIN
+
 // Loads a native library from disk.  Release it with UnloadNativeLibrary when
 // you're done.  Returns NULL on failure.
-// If |error| is not NULL, it may be filled in with an error message on error.
+// If |error| is not NULL, it may be filled in on load error if the platform

[ddorwin, 2014/03/21 20:06:32]

I think we can drop the "if the platform..." part. Maybe we can replace "may"
with "can" when the Mac implementation is fixed.

[xhwang, 2014/03/21 22:33:28]

Done.

+// supports it.
 BASE_EXPORT NativeLibrary LoadNativeLibrary(const FilePath& library_path,
-                                            std::string* error);
+                                            NativeLibraryLoadError* 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_EXPORT NativeLibrary LoadNativeLibraryDynamically(
     const FilePath& library_path);
 #endif  // OS_WIN
 
 // Unloads a native library.
 BASE_EXPORT void UnloadNativeLibrary(NativeLibrary library);
 
 // Gets a function pointer from a native library.
 BASE_EXPORT 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_EXPORT string16 GetNativeLibraryName(const string16& name);
 
 }  // namespace base
 
 #endif  // BASE_NATIVE_LIBRARY_H_