Cache the current WebPreferences on RenderViewHostImpl (try #2).

content/browser/renderer_host/render_view_host_impl.cc

 // Copyright (c) 2012 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/browser/renderer_host/render_view_host_impl.h"
 
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 181 matching lines @@
       navigations_suspended_(false),
       main_frame_routing_id_(main_frame_routing_id),
       run_modal_reply_msg_(NULL),
       run_modal_opener_id_(MSG_ROUTING_NONE),
       is_waiting_for_beforeunload_ack_(false),
       unload_ack_is_for_cross_site_transition_(false),
       sudden_termination_allowed_(false),
       render_view_termination_status_(base::TERMINATION_STATUS_STILL_RUNNING),
       virtual_keyboard_requested_(false),
       weak_factory_(this),
-      is_focused_element_editable_(false) {
+      is_focused_element_editable_(false),
+      updating_web_preferences_(false) {
   DCHECK(instance_.get());
   CHECK(delegate_);  // http://crbug.com/82827
 
   GetProcess()->EnableSendQueue();
 
   if (swapped_out) {
     rvh_state_ = STATE_SWAPPED_OUT;
   } else {
     rvh_state_ = STATE_DEFAULT;
     instance_->increment_active_view_count();
@@ skipping 69 matching lines @@
 
   // Ensure the RenderView starts with a next_page_id larger than any existing
   // page ID it might be asked to render.
   int32 next_page_id = 1;
   if (max_page_id > -1)
     next_page_id = max_page_id + 1;
 
   ViewMsg_New_Params params;
   params.renderer_preferences =
       delegate_->GetRendererPrefs(GetProcess()->GetBrowserContext());
-  params.web_preferences = delegate_->GetWebkitPrefs();
+  params.web_preferences = GetWebkitPreferences();
   params.view_id = GetRoutingID();
   params.main_frame_routing_id = main_frame_routing_id_;
   params.surface_id = surface_id();
   params.session_storage_namespace_id =
       delegate_->GetSessionStorageNamespace(instance_)->id();
   params.frame_name = frame_name;
   // Ensure the RenderView sets its opener correctly.
   params.opener_route_id = opener_route_id;
   params.swapped_out = !IsRVHStateActive(rvh_state_);
   params.proxy_routing_id = proxy_route_id;
@@ skipping 19 matching lines @@
 bool RenderViewHostImpl::IsRenderViewLive() const {
   return GetProcess()->HasConnection() && renderer_initialized_;
 }
 
 void RenderViewHostImpl::SyncRendererPrefs() {
   Send(new ViewMsg_SetRendererPrefs(GetRoutingID(),
                                     delegate_->GetRendererPrefs(
                                         GetProcess()->GetBrowserContext())));
 }
 
-WebPreferences RenderViewHostImpl::GetWebkitPrefs(const GURL& url) {
+WebPreferences RenderViewHostImpl::ComputeWebkitPrefs(const GURL& url) {
   TRACE_EVENT0("browser", "RenderViewHostImpl::GetWebkitPrefs");
   WebPreferences prefs;
 
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   prefs.javascript_enabled =
       !command_line.HasSwitch(switches::kDisableJavaScript);
   prefs.web_security_enabled =
       !command_line.HasSwitch(switches::kDisableWebSecurity);
   prefs.plugins_enabled =
@@ skipping 1068 matching lines @@
   view_->OnTextSurroundingSelectionResponse(content, start_offset, end_offset);
 }
 
 void RenderViewHostImpl::ExitFullscreen() {
   RejectMouseLockOrUnlockIfNecessary();
   // Notify delegate_ and renderer of fullscreen state change.
   OnToggleFullscreen(false);
 }
 
 WebPreferences RenderViewHostImpl::GetWebkitPreferences() {
-  return delegate_->GetWebkitPrefs();
+  if (!web_preferences_.get()) {
+    OnWebkitPreferencesChanged();
+  }
+  return *web_preferences_;
 }
 
 void RenderViewHostImpl::DisownOpener() {
   // This should only be called when swapped out.
   DCHECK(IsSwappedOut());
 
   Send(new ViewMsg_DisownOpener(GetRoutingID()));
 }
 
 void RenderViewHostImpl::UpdateWebkitPreferences(const WebPreferences& prefs) {
+  web_preferences_.reset(new WebPreferences(prefs));
   Send(new ViewMsg_UpdateWebPreferences(GetRoutingID(), prefs));
 }
 
+void RenderViewHostImpl::OnWebkitPreferencesChanged() {
+  // This is defensive code to avoid infinite loops due to code run inside

[chrishtr, 2014/08/06 16:14:58]

See additional defensive code here to avoid an infinite loop. It should never
happen,
but the severity of the problem if it happens justifies this code.

+  // UpdateWebkitPreferences() accidentally updating more preferences and thus
+  // calling back into this code. See crbug.com/398751 for one past example.
+  if (updating_web_preferences_)
+    return;
+  updating_web_preferences_ = true;
+  UpdateWebkitPreferences(delegate_->ComputeWebkitPrefs());
+  updating_web_preferences_ = false;
+}
+
 void RenderViewHostImpl::GetAudioOutputControllers(
     const GetAudioOutputControllersCallback& callback) const {
   AudioRendererHost* audio_host =
       static_cast<RenderProcessHostImpl*>(GetProcess())->audio_renderer_host();
   audio_host->GetOutputControllers(GetRoutingID(), callback);
 }
 
 void RenderViewHostImpl::ClearFocusedElement() {
   is_focused_element_editable_ = false;
   Send(new ViewMsg_ClearFocusedElement(GetRoutingID()));
@@ skipping 135 matching lines @@
   FrameTree* frame_tree = delegate_->GetFrameTree();
 
   frame_tree->ResetForMainFrameSwap();
 }
 
 void RenderViewHostImpl::SelectWordAroundCaret() {
   Send(new ViewMsg_SelectWordAroundCaret(GetRoutingID()));
 }
 
 }  // namespace content