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..767a1780a76c8c14da0249ef85a99bf852a1d9fc 100644
--- a/extensions/browser/sandboxed_unpacker.cc
+++ b/extensions/browser/sandboxed_unpacker.cc
@@ -212,6 +212,11 @@ bool ReadMessageCatalogsFromFile(const base::FilePath& extension_path,
 
 }  // namespace
 
+SandboxedUnpackerClient::SandboxedUnpackerClient(
+    const scoped_refptr<base::MessageLoopProxy>& loop)
+    : RefCountedDeleteOnMessageLoop<SandboxedUnpackerClient>(loop) {

[benwells, 2015/04/14 22:14:19]

Can you put BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI)
straight in here instead of plumbing it up from all subclasses?

[tapted, 2015/04/15 03:07:44]

Done. Turns out //extensions/browser is fine wrt DEPS. But at least this forced
me to double-check all the derived classes to ensure they're OK with the change.

Added a DCHECK_CURRENTLY_ON(BrowserThread::UI); to the constructor here, and
updated the header comment.

+}
+
 SandboxedUnpacker::SandboxedUnpacker(
     const CRXFileInfo& file,
     Manifest::Location location,