PPAPI: Make TrackedCallback more threadsafe

ppapi/proxy/file_mapping_resource.cc

Index: ppapi/proxy/file_mapping_resource.cc
diff --git a/ppapi/proxy/file_mapping_resource.cc b/ppapi/proxy/file_mapping_resource.cc
index c620c06dd29968620cce360a35868ee1fdd1dd66..b1dc27169f6f9fffa2aa2421283f4bbc0ac345c8 100644
--- a/ppapi/proxy/file_mapping_resource.cc
+++ b/ppapi/proxy/file_mapping_resource.cc
@@ -137,19 +137,7 @@ void FileMappingResource::OnMapCompleted(
     int64_t length,
     scoped_refptr<TrackedCallback> callback,
     const MapResult& map_result) {
-  if (callback->aborted()) {
-    if (map_result.result == PP_OK) {
-      // If the Map operation was successful, we need to Unmap to avoid leaks.
-      // The plugin won't get the address, so doesn't have a chance to do the
-      // Unmap.
-      PpapiGlobals::Get()->GetFileTaskRunner()->PostTask(
-          FROM_HERE,
-          base::Bind(base::IgnoreResult(&FileMappingResource::DoUnmapBlocking),
-                     map_result.address,
-                     length));
-    }
-    return;
-  }
+  // FIXME, just delete this whole file when merging.

[dmichael (off chromium), 2015/02/27 22:04:40]

When I can rebase this on top of removing FileMapping, this change will go
away...  this just makes it compile/pass by ignoring the very special case :)

[bbudge, 2015/03/05 01:29:35]

OK.

   if (map_result.result == PP_OK)
     *mapped_address_out_param = map_result.address;
   if (!callback->is_blocking())