Always destroy CrxInstaller on the UI Thread

extensions/browser/sandboxed_unpacker.cc

Index: extensions/browser/sandboxed_unpacker.cc
diff --git a/extensions/browser/sandboxed_unpacker.cc b/extensions/browser/sandboxed_unpacker.cc
index e22109a79bb69cbe706b9870d4d5a068ce526830..29d559a6775606910a3feda06653df304bd3471b 100644
--- a/extensions/browser/sandboxed_unpacker.cc
+++ b/extensions/browser/sandboxed_unpacker.cc
@@ -212,6 +212,13 @@ bool ReadMessageCatalogsFromFile(const base::FilePath& extension_path,
 
 }  // namespace
 
+SandboxedUnpackerClient::SandboxedUnpackerClient()
+    : RefCountedDeleteOnMessageLoop<SandboxedUnpackerClient>(
+          content::BrowserThread::GetMessageLoopProxyForThread(
+              content::BrowserThread::UI)) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+}
+
 SandboxedUnpacker::SandboxedUnpacker(
     const CRXFileInfo& file,
     Manifest::Location location,