Use a resource throttle to implement shouldOverrideUrlLoading.

android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc

Index: android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc
diff --git a/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc b/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc
index 02160ce9f13534c9343f7e79c147ebea1f3a7f43..2eb962d31f47265f2d09e3668fa584c8178ad56a 100644
--- a/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc
+++ b/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc
@@ -226,10 +226,11 @@ void AwResourceDispatcherHostDelegate::RequestBeginning(
   throttles->push_back(new IoThreadClientThrottle(
       request_info->GetChildID(), request_info->GetRenderFrameID(), request));
 
-  // We allow intercepting only navigations within main frames. This
-  // is used to post onPageStarted. We handle shouldOverrideUrlLoading
-  // via a sync IPC.
-  if (resource_type == content::RESOURCE_TYPE_MAIN_FRAME) {
+  if (resource_type == content::RESOURCE_TYPE_MAIN_FRAME ||
+      (resource_type == content::RESOURCE_TYPE_SUB_FRAME &&
+       !request->url().SchemeIs(url::kHttpScheme) &&
+       !request->url().SchemeIs(url::kHttpsScheme) &&
+       !request->url().SchemeIs(url::kAboutScheme))) {
     throttles->push_back(InterceptNavigationDelegate::CreateThrottleFor(
         request));
   } else {