Implement CachedMetadata handling on MojoAsyncResourceHandler

content/child/url_loader_client_impl.cc

Index: content/child/url_loader_client_impl.cc
diff --git a/content/child/url_loader_client_impl.cc b/content/child/url_loader_client_impl.cc
index 04aee613ace7c63b19db4b3b8c5f995f9cf9ba30..f41f661e079f147b83637d35c9e1851f633bb89f 100644
--- a/content/child/url_loader_client_impl.cc
+++ b/content/child/url_loader_client_impl.cc
@@ -134,6 +134,13 @@ void URLLoaderClientImpl::OnDataDownloaded(int64_t data_len,
   Dispatch(ResourceMsg_DataDownloaded(request_id_, data_len, encoded_data_len));
 }
 
+void URLLoaderClientImpl::OnReceiveCachedMetadata(
+    const std::vector<uint8_t>& data) {
+  const char* ptr = reinterpret_cast<const char*>(data.data());

[mmenke, 2017/01/17 18:39:57]

Again, suggest replacing ptr with data

[yhirano, 2017/01/18 06:22:42]

I'm using data_ptr as we are already using the name.

+  Dispatch(ResourceMsg_ReceivedCachedMetadata(
+      request_id_, std::vector<char>(ptr, ptr + data.size())));

[dcheng, 2017/01/14 11:30:17]

And I guess this is another copy =(

Is there any way we can be consistent with our types here? It's uint8_t on the
sending side and char on the receiving side.

[yhirano, 2017/01/16 05:25:46]

This is needed to reuse the current ResourceDispatcher code. I want to do that
during migration unless there's a significant performance regression. tzik@ will
measure the performance in this quarter, so I would like to fix performance
regressions after that. Are you fine with the plan?
It's char on both sending and receiving sides. You can see reinterpret_cast here
and in MojoAsyncResourceHandler.

[dcheng, 2017/01/18 00:23:53]

Sort of... we have to reinterpret_cast the original buffer to a uint8_t* to
construct a std::vector<uint8_t> out of it, and then we have to reinterpret_cast
it back on the other side.

It seems like we should be fixing the representation here to use
std::vector<uint8_t> throughout (though that's obviously out of scope of this
patch)

[yhirano, 2017/01/18 06:22:42]

Acknowledged.

+}
+
 void URLLoaderClientImpl::OnTransferSizeUpdated(int32_t transfer_size_diff) {
   if (is_deferred_) {
     accumulated_transfer_size_diff_during_deferred_ += transfer_size_diff;