Listen to didReceiveResponse() to get the response in WebViewPlugin.

components/plugins/renderer/webview_plugin.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/plugins/renderer/webview_plugin.h"
 
 #include <stddef.h>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
@@ skipping 77 matching lines @@
 }
 
 WebViewPlugin::~WebViewPlugin() {
   DCHECK(!weak_factory_.HasWeakPtrs());
   web_frame_widget_->close();
   web_view_->close();
   web_frame_->close();
 }
 
 void WebViewPlugin::ReplayReceivedData(WebPlugin* plugin) {
-  const WebURLResponse& response = web_frame_->dataSource()->response();
-  if (!response.isNull()) {

[tommycli, 2016/09/16 17:38:03]

If I understand correctly, WebPlugin::didReceiveResponse() is never called, and
WebFrameClient::didReceiveResponse() IS called, but with irrelevant,
inappropriate data...

I realize there's a hairy diamond inheritance problem -- but can we add an
explicit NOTREACHED() for WebPlugin::didReceiveResponse() that won't be
triggered by the WebFrameClient::didReceiveResponse()?

[Nate Chapin, 2016/09/16 17:49:40]

Correct.
There may be a way, but I'd need to do some research or get some guidance: my
C++ knowledge is minimal in this area.

[tommycli, 2016/09/16 18:08:26]

Okay, here's one suggestion:

Make the WebFrameClient portion a delegate. Have WebViewPlugin own a member
frame_client_ that implements the interface. Maybe it's an inner class or
something.

Now WebViewPlugin::didReceiveResponse should only override
WebPlugin::didReceiveResponse and you can put NOTREACHED in there.

Thanks for investigating, Tommy

-    plugin->didReceiveResponse(response);
-    size_t total_bytes = 0;
-    for (std::list<std::string>::iterator it = data_.begin(); it != data_.end();
-         ++it) {
-      plugin->didReceiveData(
-          it->c_str(), base::checked_cast<int, size_t>(it->length()));
-      total_bytes += it->length();
-    }
-    UMA_HISTOGRAM_MEMORY_KB(

[tommycli, 2016/09/16 17:38:03]

Are these the only places these UMAs are logged? If so, can we remove from
histograms.xml also?

[Nate Chapin, 2016/09/16 17:49:39]

I don't see any related histograms.xml entries?

[tommycli, 2016/09/16 18:08:26]

They don't appear under UMA either. These must just be orphans (safe to delete).

-        "PluginDocument.Memory",
-        (base::checked_cast<int, size_t>(total_bytes / 1024)));
-    UMA_HISTOGRAM_COUNTS(
-        "PluginDocument.NumChunks",
-        (base::checked_cast<int, size_t>(data_.size())));
-  }
   // We need to transfer the |focused_| to new plugin after it loaded.
   if (focused_) {
     plugin->updateFocus(true, blink::WebFocusTypeNone);
   }
   if (finished_loading_) {
     plugin->didFinishLoading();
   }
   if (error_) {
     plugin->didFailLoading(*error_);
   }
@@ skipping 224 matching lines @@
   if (!delegate_)
     return;
 
   // The delegate may instantiate a new plugin.
   delegate_->OnUnobscuredRectUpdate(gfx::Rect(unobscured_rect));
   // The delegate may have dirtied style and layout of the WebView.
   // See for example the resizePoster function in plugin_poster.html.
   // Run the lifecycle now so that it is clean.
   web_view_->updateAllLifecyclePhases();
 }