Pepper: Add append support to FileIO.

ppapi/shared_impl/file_type_conversion.cc

Index: ppapi/shared_impl/file_type_conversion.cc
diff --git a/ppapi/shared_impl/file_type_conversion.cc b/ppapi/shared_impl/file_type_conversion.cc
index 87edeb0cd51b64eadd5ed055492f29b3f04da193..f9d65704ab9265056792fdc7c2632d0c8621130a 100644
--- a/ppapi/shared_impl/file_type_conversion.cc
+++ b/ppapi/shared_impl/file_type_conversion.cc
@@ -45,6 +45,7 @@ bool PepperFileOpenFlagsToPlatformFileFlags(int32_t pp_open_flags,
   bool pp_create = !!(pp_open_flags & PP_FILEOPENFLAG_CREATE);
   bool pp_truncate = !!(pp_open_flags & PP_FILEOPENFLAG_TRUNCATE);
   bool pp_exclusive = !!(pp_open_flags & PP_FILEOPENFLAG_EXCLUSIVE);
+  bool pp_append = !!(pp_open_flags & PP_FILEOPENFLAG_APPEND);
 
   int flags = 0;
   if (pp_read)
@@ -53,6 +54,11 @@ bool PepperFileOpenFlagsToPlatformFileFlags(int32_t pp_open_flags,
     flags |= base::PLATFORM_FILE_WRITE;
     flags |= base::PLATFORM_FILE_WRITE_ATTRIBUTES;
   }
+  if (pp_append) {
+    if (pp_write)
+      return false;
+    flags |= base::PLATFORM_FILE_APPEND;
+  }
 
   if (pp_truncate && !pp_write)
     return false;