Return frame/origin-bound URLLoaderFactory from WebViewPlugin/Helper.

This CL modifies WebViewPlugin::WebViewHelper::CreateURLLoaderFactory
method so that it delegates creation of URLLoaderFactory to the frame
that hosts the plugin.

Bug: 891872
Change-Id: I002503730f98adbced92d61c7d74eb53f4865e98
Reviewed-on: https://chromium-review.googlesource.com/c/1259824Reviewed-by: Tommy Li <tommycli@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608632}

components/plugins/renderer/webview_plugin.cc

@@ -345,7 +345,11 @@ void WebViewPlugin::WebViewHelper::ScheduleAnimation() {
 
 std::unique_ptr<blink::WebURLLoaderFactory>
 WebViewPlugin::WebViewHelper::CreateURLLoaderFactory() {
-  return blink::Platform::Current()->CreateDefaultURLLoaderFactory();
+  return plugin_->Container()
+      ->GetDocument()
+      .GetFrame()
+      ->Client()
+      ->CreateURLLoaderFactory();
 }
 
 void WebViewPlugin::WebViewHelper::DidClearWindowObject() {

third_party/blink/public/platform/platform.h

@@ -344,7 +344,7 @@ class BLINK_PLATFORM_EXPORT Platform {
   // get a factory bundle from the browser process, and compose a new factory
   // using both the bundle and this default.
   //
-  // TODO(kinuko): See if we can deprecate this too.
+  // TODO(kinuko): https://crbug.com/891872: See if we can deprecate this too.
   virtual std::unique_ptr<WebURLLoaderFactory> CreateDefaultURLLoaderFactory() {
     return nullptr;
   }