PlzNavigate: make MHTML iframe load working.

content/common/navigation_params.cc

 // Copyright 2014 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 "content/common/navigation_params.h"
 
 #include "base/logging.h"
 #include "build/build_config.h"
 #include "content/common/service_worker/service_worker_types.h"
 #include "content/public/common/appcache_info.h"
@@ skipping 14 matching lines @@
   if (url.SchemeIs(url::kJavaScriptScheme) || url.is_empty() ||
       url.SchemeIs(url::kContentIDScheme) || url == content::kAboutSrcDocURL) {
     return false;
   }
 
   for (const auto& scheme : url::GetEmptyDocumentSchemes()) {
     if (url.SchemeIs(scheme))
       return false;
   }
 
+  // For you information, even though a "data:" url doesn't generate actual
+  // network requests, it is handled by the network stack and so must return
+  // true. The reason is that a few "data:" urls can't be handled locally. For
+  // instance:
+  // - the ones that result in downloads.
+  // - the ones that are invalid. An error page must be served instead.
+  // - the ones that have an unsupported MIME type.
+  // - the ones that target the top-level frame on Android.
+
   return true;
 }
 
 SourceLocation::SourceLocation() : line_number(0), column_number(0) {}
 
 SourceLocation::SourceLocation(const std::string& url,
                                unsigned int line_number,
                                unsigned int column_number)
     : url(url), line_number(line_number), column_number(column_number) {}
 
@@ skipping 176 matching lines @@
     const RequestNavigationParams& request_params)
     : common_params(common_params),
       start_params(start_params),
       request_params(request_params) {
 }
 
 NavigationParams::~NavigationParams() {
 }
 
 }  // namespace content