Ensure static BrowserContext methods only get called on the UI thread.

content/browser/resource_context_impl.cc

Index: content/browser/resource_context_impl.cc
===================================================================
--- content/browser/resource_context_impl.cc	(revision 145676)
+++ content/browser/resource_context_impl.cc	(working copy)
@@ -175,6 +175,7 @@
 }  // namespace
 
 AppCacheService* ResourceContext::GetAppCacheService(ResourceContext* context) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return UserDataAdapter<ChromeAppCacheService>::Get(
       context, kAppCacheServicKeyName);
 }
@@ -194,35 +195,41 @@
 
 BlobStorageController* GetBlobStorageControllerForResourceContext(
     ResourceContext* resource_context) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return GetChromeBlobStorageContextForResourceContext(resource_context)->
       controller();
 }
 
 DatabaseTracker* GetDatabaseTrackerForResourceContext(
     ResourceContext* resource_context) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return UserDataAdapter<DatabaseTracker>::Get(
       resource_context, kDatabaseTrackerKeyName);
 }
 
 FileSystemContext* GetFileSystemContextForResourceContext(
     ResourceContext* resource_context) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return UserDataAdapter<FileSystemContext>::Get(
       resource_context, kFileSystemContextKeyName);
 }
 
 IndexedDBContextImpl* GetIndexedDBContextForResourceContext(
     ResourceContext* resource_context) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return UserDataAdapter<IndexedDBContextImpl>::Get(
       resource_context, kIndexedDBContextKeyName);
 }
 
 ChromeBlobStorageContext* GetChromeBlobStorageContextForResourceContext(
     ResourceContext* resource_context) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return UserDataAdapter<ChromeBlobStorageContext>::Get(
       resource_context, kBlobStorageContextKeyName);
 }
 
 HostZoomMap* GetHostZoomMapForResourceContext(ResourceContext* context) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return static_cast<NonOwningZoomData*>(
       context->GetUserData(kHostZoomMapKeyName))->host_zoom_map();
 }