[not part of build] Use nsIObserverService to shut down cache before XPCOM is shut down. r=gordon

netwerk/cache/src/nsCacheService.cpp

@@ -35,13 +35,14 @@
 #include "nsIEventQueue.h"
 #include "nsProxiedService.h"
 #include "nsICacheVisitor.h"
+#include "nsIObserverService.h"
 
 static NS_DEFINE_CID(kEventQueueServiceCID, NS_EVENTQUEUESERVICE_CID);
 static NS_DEFINE_CID(kProxyObjectManagerCID, NS_PROXYEVENT_MANAGER_CID);
 
 nsCacheService *   nsCacheService::gService = nsnull;
 
-NS_IMPL_THREADSAFE_ISUPPORTS1(nsCacheService, nsICacheService)
+NS_IMPL_THREADSAFE_ISUPPORTS2(nsCacheService, nsICacheService, nsIObserver)
 
 nsCacheService::nsCacheService()
     : mCacheServiceLock(nsnull),
@@ -103,6 +104,14 @@ nsCacheService::Init()
     rv = mDiskDevice->Init();
     if (NS_FAILED(rv)) goto error;
 
+    // observer XPCOM shutdown.
+    {
+        nsCOMPtr<nsIObserverService> observerService = do_GetService(NS_OBSERVERSERVICE_CONTRACTID, &rv);
+        if (NS_SUCCEEDED(rv)) {
+            observerService->AddObserver(this, NS_LITERAL_STRING(NS_XPCOM_SHUTDOWN_OBSERVER_ID).get());
+        }
+    }
+    
     return NS_OK;
 
  error:
@@ -680,6 +689,11 @@ nsCacheService::ProcessPendingRequests(nsCacheEntry * entry)
     return NS_OK;
 }
 
+NS_IMETHODIMP nsCacheService::Observe(nsISupports *aSubject, const PRUnichar *aTopic, const PRUnichar *someData)
+{
+    return Shutdown();
+}
+
 
 /**
  * Cache Service Utility Functions

netwerk/cache/src/nsCacheService.h

@@ -32,6 +32,7 @@
 #include "nsCacheSession.h"
 #include "nsCacheDevice.h"
 #include "nsCacheEntry.h"
+#include "nsIObserver.h"
 
 class nsCacheRequest;
 
@@ -40,11 +41,12 @@ class nsCacheRequest;
  *  nsCacheService
  */
 
-class nsCacheService : public nsICacheService
+class nsCacheService : public nsICacheService, public nsIObserver
 {
 public:
     NS_DECL_ISUPPORTS
     NS_DECL_NSICACHESERVICE
+    NS_DECL_NSIOBSERVER
     
     nsCacheService();
     virtual ~nsCacheService();