Fix race condition in utility process clients

content/browser/utility_process_host.h

Index: content/browser/utility_process_host.h
diff --git a/content/browser/utility_process_host.h b/content/browser/utility_process_host.h
index 779c8499f10b31d122de37739e45709315195b30..8b9d4695fb338cc2f9d2417b1c3a8b80ed9b9b29 100644
--- a/content/browser/utility_process_host.h
+++ b/content/browser/utility_process_host.h
@@ -12,6 +12,7 @@
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/process_util.h"
+#include "base/memory/weak_ptr.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/browser_child_process_host_delegate.h"
 #include "content/public/browser/browser_thread.h"
@@ -28,7 +29,8 @@ class BrowserChildProcessHostImpl;
 // then finish with EndBatchMode().
 class CONTENT_EXPORT UtilityProcessHost
     : public content::BrowserChildProcessHostDelegate,
-      public IPC::Message::Sender {
+      public IPC::Message::Sender,
+      public base::SupportsWeakPtr<UtilityProcessHost> {

[jam, 2012/01/26 03:56:18]

i dont think this is necessary. you can already get notified through the
Client::OnProcessCrashed callback.

[dgrogan, 2012/01/26 04:17:39]

Client::OnProcessCrashed is posted to the IO thread asynchronously but
UtilityProcessHost is deleted synchronously, so there's a tiny race condition
that could be triggered if a task is already queued up on the IO thread that
uses KeyUtilityClientImpl::utility_process_host_.

[jam, 2012/01/26 05:17:00]

ah, good point. There are other places that hang on to UtilityProcessHost. Can
you either fix them or file bugs against those owners? And also add a warning in
the header file about this issue so others don't repeat it?

[dgrogan, 2012/01/26 23:17:58]

Done.

  public:
   // An interface to be implemented by consumers of the utility process to
   // get results back.  All functions are called on the thread passed along
@@ -87,7 +89,7 @@ class CONTENT_EXPORT UtilityProcessHost
 
   // BrowserChildProcessHost:
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
-  virtual void OnProcessCrashed(int exit_code) OVERRIDE;
+  virtual void OnProcessCrashedOrWasKilled(int exit_code) OVERRIDE;
 
   // A pointer to our client interface, who will be informed of progress.
   scoped_refptr<Client> client_;