Remove about:srcdoc url conversion.

content/browser/frame_host/render_frame_proxy_host.cc

Index: content/browser/frame_host/render_frame_proxy_host.cc
diff --git a/content/browser/frame_host/render_frame_proxy_host.cc b/content/browser/frame_host/render_frame_proxy_host.cc
index b8ec5d390ec6a0fe9e84b550a2fa927d9bbb1903..136da8bd66f7a2249fc6e0747232206e36fb393c 100644
--- a/content/browser/frame_host/render_frame_proxy_host.cc
+++ b/content/browser/frame_host/render_frame_proxy_host.cc
@@ -21,6 +21,7 @@
 #include "content/common/frame_messages.h"
 #include "content/common/frame_owner_properties.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/common/url_constants.h"
 #include "ipc/ipc_message.h"
 
 namespace content {
@@ -246,7 +247,8 @@ void RenderFrameProxyHost::OnDetach() {
 void RenderFrameProxyHost::OnOpenURL(
     const FrameHostMsg_OpenURL_Params& params) {
   GURL validated_url(params.url);
-  GetProcess()->FilterURL(false, &validated_url);
+  if (validated_url != GURL(content::kAboutSrcDocURL))
+    GetProcess()->FilterURL(false, &validated_url);
 
   // Verify that we are in the same BrowsingInstance as the current
   // RenderFrameHost.