Fix IndexedDB race condition during shutdown.

chrome/browser/in_process_webkit/webkit_context.cc

Index: chrome/browser/in_process_webkit/webkit_context.cc
diff --git a/chrome/browser/in_process_webkit/webkit_context.cc b/chrome/browser/in_process_webkit/webkit_context.cc
index 0c72346822a10cccc5ea96eb1efdef5b7f3011e7..36a8d7e906e7f589c72044152d91f0cdf71c78cc 100644
--- a/chrome/browser/in_process_webkit/webkit_context.cc
+++ b/chrome/browser/in_process_webkit/webkit_context.cc
@@ -5,9 +5,45 @@
 #include "chrome/browser/in_process_webkit/webkit_context.h"
 
 #include "base/command_line.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/task.h"
 #include "chrome/browser/browser_thread.h"
 #include "chrome/browser/profiles/profile.h"
 
+namespace {
+
+template<typename T>
+class DeletionTask : public Task {
+ public:
+  DeletionTask(T* object, base::WaitableEvent& event)
+      : object_(object),
+        event_(event) {}
+
+  // From Task.
+  virtual void Run() {
+    delete object_;
+    event_.Signal();
+  };
+
+ private:
+  T* object_;
+  base::WaitableEvent& event_;

[jorlow, 2011/01/12 17:08:21]

Why not a pointer?  That seems more typical.

+};
+
+template <typename T>
+void DeleteOnThread(BrowserThread::ID thread_id, T* object) {

[jorlow, 2011/01/12 17:08:21]

This is doing more than deleting on a particular thread.  Maybe the name should
somehow mention that it can block.

+  base::WaitableEvent event(true, false);
+  Task* delete_task = new DeletionTask<T>(object, event);
+
+  if (BrowserThread::PostTask(thread_id, FROM_HERE, delete_task)) {

[jorlow, 2011/01/12 17:08:21]

no {}'s

+    event.Wait();
+  } else {
+    delete object;
+  }
+}
+
+}  // namespace
+
 WebKitContext::WebKitContext(Profile* profile, bool clear_local_state_on_exit)
     : data_path_(profile->IsOffTheRecord() ? FilePath() : profile->GetPath()),
       is_incognito_(profile->IsOffTheRecord()),
@@ -34,11 +70,7 @@ WebKitContext::~WebKitContext() {
 
   indexed_db_context_->set_clear_local_state_on_exit(
       clear_local_state_on_exit_);
-  IndexedDBContext* indexed_db_context = indexed_db_context_.release();
-  if (!BrowserThread::DeleteSoon(
-          BrowserThread::WEBKIT, FROM_HERE, indexed_db_context)) {
-    delete indexed_db_context;
-  }
+  DeleteOnThread(BrowserThread::WEBKIT, indexed_db_context_.release());

[jorlow, 2011/01/12 17:08:21]

Hm...so we're going to block the io thread on the WebKit?  Is there any way to
avoid this?  Could we at least do the wait later or something?

 }
 
 void WebKitContext::PurgeMemory() {