Make browser_handles_top_level_requests synchronous.

content/browser/renderer_host/render_view_host_impl.cc

Index: content/browser/renderer_host/render_view_host_impl.cc
diff --git a/content/browser/renderer_host/render_view_host_impl.cc b/content/browser/renderer_host/render_view_host_impl.cc
index e31de0f182530c5e9c400978464681233c61a479..9c6080368ae92768758eba5278d8ac1c1961a886 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -828,6 +828,8 @@ bool RenderViewHostImpl::OnMessageReceived(const IPC::Message& msg) {
     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,
@@ -1160,6 +1162,21 @@ void RenderViewHostImpl::OnMsgOpenURL(const GURL& url,
       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);