Pepper: Initialize PP_ImageDataDesc when creating ImageData.

ppapi/proxy/ppb_image_data_proxy.cc

Index: ppapi/proxy/ppb_image_data_proxy.cc
diff --git a/ppapi/proxy/ppb_image_data_proxy.cc b/ppapi/proxy/ppb_image_data_proxy.cc
index 87b49a777a1caf669be091172a24d52acfdecf0a..51751668f228dd9fef77218feabfcf55010eef47 100644
--- a/ppapi/proxy/ppb_image_data_proxy.cc
+++ b/ppapi/proxy/ppb_image_data_proxy.cc
@@ -494,7 +494,9 @@ PP_Resource PPB_ImageData_Proxy::CreateProxyResource(
   }
 
   HostResource result;
-  PP_ImageDataDesc desc;
+  // Initialize desc so we don't send unitialized memory over IPC.
+  // https://crbug.com/391023.
+  PP_ImageDataDesc desc = {};
   switch (type) {
     case PPB_ImageData_Shared::SIMPLE: {
       ppapi::proxy::SerializedHandle image_handle_wrapper;