[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 5d6161e8cf2c5afae4225e9b62b2c37a6492f961..136ea122d9279b2e3bcfd606eee7640a5d891c5c 100644
--- a/ppapi/proxy/file_system_resource.cc
+++ b/ppapi/proxy/file_system_resource.cc
@@ -175,8 +175,7 @@ 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);
@@ -185,12 +184,12 @@ void FileSystemResource::ReserveQuota(int64_t amount) {
       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));
 }