[Pepper] Wire up append mode writing support of FileIO

ppapi/proxy/file_system_resource.cc

Index: ppapi/proxy/file_system_resource.cc
diff --git a/ppapi/proxy/file_system_resource.cc b/ppapi/proxy/file_system_resource.cc
index 18abc0e9971d68549b61f47e74b60a79d9a9a051..b746974061b62ae863fa4c6bd9938c25ded6886e 100644
--- a/ppapi/proxy/file_system_resource.cc
+++ b/ppapi/proxy/file_system_resource.cc
@@ -175,20 +175,19 @@ void FileSystemResource::ReserveQuota(int64_t amount) {
   DCHECK(!reserving_quota_);
   reserving_quota_ = true;
 
-  // TODO(tzik): Use FileGrowthMap here after the IPC signature changed.
-  FileSizeMap file_sizes;
+  FileGrowthMap file_growths;
   for (std::set<PP_Resource>::iterator it = files_.begin();
        it != files_.end(); ++it) {
     EnterResourceNoLock<PPB_FileIO_API> enter(*it, true);
     if (enter.failed())
       continue;
     PPB_FileIO_API* file_io_api = enter.object();
-    file_sizes[*it] =
-        file_io_api->GetMaxWrittenOffset() +
-        file_io_api->GetAppendModeWriteAmount();
+    file_growths[*it] = FileGrowth(
+        file_io_api->GetMaxWrittenOffset(),
+        file_io_api->GetAppendModeWriteAmount());
   }
   Call<PpapiPluginMsg_FileSystem_ReserveQuotaReply>(BROWSER,
-      PpapiHostMsg_FileSystem_ReserveQuota(amount, file_sizes),
+      PpapiHostMsg_FileSystem_ReserveQuota(amount, file_growths),
       base::Bind(&FileSystemResource::ReserveQuotaComplete,
                  this));
 }