Don't reenter Webkit, while it waits for outgoing sync calls to complete. This

fixes bug http://code.google.com/p/chromium/issues/detail?id=4582, which is a crash in the renderer process, which occurs when the renderer receives a sync message requesting accessibility information from the browser, while it waits
for the PluginDestroyed sync call to unwind.

The ViewMsg_GetAccessibilityInfo has a timeout associated with it, which indicates that it is ok for the call to fail. We now turn off the unblock flag on the sync message which will ensure that it does not reenter Webkit in this scenario.

R=jcampan
Bug=4582

Review URL: http://codereview.chromium.org/12402

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@5927 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 4 insertions, 0 deletions

diff --git a/chrome/browser/browser_accessibility_manager.cc b/chrome/browser/browser_accessibility_manager.cc
index 51b7654..a825995 100644
--- a/chrome/browser/browser_accessibility_manager.cc
+++ b/chrome/browser/browser_accessibility_manager.cc
@@ -108,6 +108,10 @@ bool BrowserAccessibilityManager::RequestAccessibilityInfo(
       members->render_widget_host_->process()->channel()) {
     // Necessary for the send to keep the UI responsive.
     msg->EnableMessagePumping();
+    // By default sync calls are unblocking, i.e if the receiver is an outgoing
+    // sync call, it will process received sync calls. Webkit is not reentrant.
+    // We don't want to reenter Webkit if it is in an outgoing sync call.
+    msg->set_unblock(false);
     success = members->render_widget_host_->process()->channel()->
         SendWithTimeout(msg, kAccessibilityMessageTimeOut);
   }