Make browser_handles_top_level_requests synchronous.

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 810 matching lines @@
     IPC_MESSAGE_HANDLER(ViewHostMsg_DidChangeLoadProgress,
                         OnMsgDidChangeLoadProgress)
     IPC_MESSAGE_HANDLER(ViewHostMsg_DocumentAvailableInMainFrame,
                         OnMsgDocumentAvailableInMainFrame)
     IPC_MESSAGE_HANDLER(ViewHostMsg_DocumentOnLoadCompletedInMainFrame,
                         OnMsgDocumentOnLoadCompletedInMainFrame)
     IPC_MESSAGE_HANDLER(ViewHostMsg_ContextMenu, OnMsgContextMenu)
     IPC_MESSAGE_HANDLER(ViewHostMsg_ToggleFullscreen,
                         OnMsgToggleFullscreen)
     IPC_MESSAGE_HANDLER(ViewHostMsg_OpenURL, OnMsgOpenURL)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_ShouldIgnoreNavigation,
+                        OnMsgShouldIgnoreNavigation)
     IPC_MESSAGE_HANDLER(ViewHostMsg_DidContentsPreferredSizeChange,
                         OnMsgDidContentsPreferredSizeChange)
     IPC_MESSAGE_HANDLER(ViewHostMsg_DidChangeScrollbarsForMainFrame,
                         OnMsgDidChangeScrollbarsForMainFrame)
     IPC_MESSAGE_HANDLER(ViewHostMsg_DidChangeScrollOffsetPinningForMainFrame,
                         OnMsgDidChangeScrollOffsetPinningForMainFrame)
     IPC_MESSAGE_HANDLER(ViewHostMsg_DidChangeNumWheelEvents,
                         OnMsgDidChangeNumWheelEvents)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(ViewHostMsg_RunJavaScriptMessage,
                                     OnMsgRunJavaScriptMessage)
@@ skipping 311 matching lines @@
                                       const content::Referrer& referrer,
                                       WindowOpenDisposition disposition,
                                       int64 source_frame_id) {
   GURL validated_url(url);
   FilterURL(ChildProcessSecurityPolicyImpl::GetInstance(),
             GetProcess()->GetID(), false, &validated_url);
 
   delegate_->RequestOpenURL(
       validated_url, referrer, disposition, source_frame_id);
 }
 

[darin (slow to review), 2012/04/16 15:47:11]

This creates a dead-lock.  It is not valid to handle synchronous IPCs messages,
sent by the renderer's main thread, on the browser's main thread.

I think you should also look hard at avoiding this synchronous IPC altogether. 

[mkosiba (inactive), 2012/04/16 16:15:08]

Is is a guaranteed deadlock or only under certain conditions? We've had a change
similar to this one in Chrome on Android for a while and it seems to work ok...
For the URL overriding in Chrome on Android we effectively need to 'park' the
navigation while we check (on the UI thread) whether we want to cancel it or
not. The only alternative I can think of is to modify the
decidePolicyForNavigation flow to be asynchronous (WebKit supports it in
FrameLoaderClientImpl::dispatchDecidePolicyForNavigationAction). Doing that
would probably add some 'interesting' states for the renderer and navigation
code.

+void RenderViewHostImpl::OnMsgShouldIgnoreNavigation(
+    const GURL& url,
+    const content::Referrer& referrer,
+    WindowOpenDisposition disposition,
+    int64 source_frame_id,
+    bool is_content_initiated,
+    bool* result) {
+  GURL validated_url(url);
+  FilterURL(ChildProcessSecurityPolicyImpl::GetInstance(),
+            GetProcess()->GetID(), false, &validated_url);
+  *result = delegate_->ShouldIgnoreNavigation(validated_url, referrer,
+                                              disposition, source_frame_id,
+                                              is_content_initiated);
+}
+
 void RenderViewHostImpl::OnMsgDidContentsPreferredSizeChange(
     const gfx::Size& new_size) {
   delegate_->UpdatePreferredSize(new_size);
 }
 
 void RenderViewHostImpl::OnRenderAutoResized(const gfx::Size& new_size) {
   delegate_->ResizeDueToAutoResize(new_size);
 }
 
 void RenderViewHostImpl::OnMsgDidChangeScrollbarsForMainFrame(
@@ skipping 553 matching lines @@
   // can cause navigations to be ignored in OnMsgNavigate.
   is_waiting_for_beforeunload_ack_ = false;
   is_waiting_for_unload_ack_ = false;
 }
 
 void RenderViewHostImpl::ClearPowerSaveBlockers() {
   STLDeleteValues(&power_save_blockers_);
 }
 
 }  // namespace content