Issue 1669 - Report blocked object subrequests as failed, not as empty HTML

src/plugin/PluginWbPassThrough.cpp

 #include "PluginStdAfx.h"
 
 #include "PluginWbPassThrough.h"
 #include "PluginClient.h"
 #include "PluginClientFactory.h"
 #include "PluginFilter.h"
 #include "PluginSettings.h"
 #include "PluginClass.h"
 #include "PluginSystem.h"
 #include <WinInet.h>
@@ skipping 345 matching lines @@
   return m_spInternetProtocolSink ? m_spInternetProtocolSink->ReportProgress(ulStatusCode, szStatusText) : S_OK;
 }
 
 STDMETHODIMP WBPassthruSink::ReportResult(/* [in] */ HRESULT hrResult, /* [in] */ DWORD dwError, /* [in] */ LPCWSTR szResult)
 {
   if (m_blockedInTransaction)
   {
     // Don't notify the client about aborting of the operation, thus don't call BaseClass::ReportResult.
     // Current method is called by the original protocol implementation and we are intercepting the
     // call here and eating it, we will call the proper ReportResult later by ourself.
-    return S_OK;
+    // NOTE: Feeding custom HTML to Flash, instead of original object subrequest
+    // doesn't have much sense. It also can manifest in unwanted result
+    // like video being blocked (See https://issues.adblockplus.org/ticket/1669)
+    // So we report blocked object subrequests as failed, not just empty HTML.
+    if (m_contentType != CFilter::contentTypeObjectSubrequest)
+    {
+      return S_OK;
+    }
   }
   return BaseClass::ReportResult(hrResult, dwError, szResult);
 }
 
 
 WBPassthru::WBPassthru()
   : m_shouldSupplyCustomContent(false)
 {
 }
 
 STDMETHODIMP WBPassthru::Start(LPCWSTR szUrl, IInternetProtocolSink *pOIProtSink,
     IInternetBindInfo *pOIBindInfo, DWORD grfPI, HANDLE_PTR dwReserved)
 {
   ATLASSERT(m_spInternetProtocol != 0);
   if (!m_spInternetProtocol)
   {
     return E_UNEXPECTED;
   }
 
   return OnStart(szUrl, pOIProtSink, pOIBindInfo, grfPI, dwReserved, m_spInternetProtocol);
 }
 
 STDMETHODIMP WBPassthru::Read(/* [in, out] */ void *pv,/* [in] */ ULONG cb,/* [out] */ ULONG *pcbRead)
 {
   WBPassthruSink* pSink = GetSink();
   return pSink->OnRead(pv, cb, pcbRead);
 }