Make tests that rely on getting a temp dir exit if they don't.

webkit/appcache/appcache_database_unittest.cc

Index: webkit/appcache/appcache_database_unittest.cc
diff --git a/webkit/appcache/appcache_database_unittest.cc b/webkit/appcache/appcache_database_unittest.cc
index f02402608b7d8413107ed3b1c8e0bbd24ea1466b..94db8137ec216a91879f7433c92a9e9a601be499 100644
--- a/webkit/appcache/appcache_database_unittest.cc
+++ b/webkit/appcache/appcache_database_unittest.cc
@@ -54,7 +54,7 @@ TEST(AppCacheDatabaseTest, LazyOpen) {
 TEST(AppCacheDatabaseTest, ReCreate) {
   // Real files on disk for this test.
   ScopedTempDir temp_dir;
-  EXPECT_TRUE(temp_dir.CreateUniqueTempDir());
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
   const FilePath kDbFile = temp_dir.path().AppendASCII("appcache.db");
   const FilePath kNestedDir = temp_dir.path().AppendASCII("nested");
   const FilePath kOtherFile =  kNestedDir.AppendASCII("other_file");