Fix some potential after free errors on TestCompletionCallback

It's illegal to destroy a TestCompletionCallback while a callback is
pending. Stop this badness by removing test assertions that could
cause this.

R=rvargas
BUG=None

Review URL: https://chromiumcodereview.appspot.com/16480002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@208749 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/net/http/http_cache_unittest.cc b/net/http/http_cache_unittest.cc
index 14099c7..b207978 100644
--- a/net/http/http_cache_unittest.cc
+++ b/net/http/http_cache_unittest.cc
@@ -5935,17 +5935,22 @@
   EXPECT_EQ(net::ERR_IO_PENDING,
             trans->Start(&info, callback.callback(), net::BoundNetLog()));
 
-  ASSERT_TRUE(cache.network_layer()->last_transaction());
-  EXPECT_EQ(net::LOW,
-            cache.network_layer()->last_create_transaction_priority());
-  EXPECT_EQ(net::LOW,
-            cache.network_layer()->last_transaction()->priority());
+  EXPECT_TRUE(cache.network_layer()->last_transaction());
+  if (cache.network_layer()->last_transaction()) {
+    EXPECT_EQ(net::LOW,
+              cache.network_layer()->last_create_transaction_priority());
+    EXPECT_EQ(net::LOW,
+              cache.network_layer()->last_transaction()->priority());
+  }
 
   trans->SetPriority(net::HIGHEST);
-  EXPECT_EQ(net::LOW,
-            cache.network_layer()->last_create_transaction_priority());
-  EXPECT_EQ(net::HIGHEST,
-            cache.network_layer()->last_transaction()->priority());
+
+  if (cache.network_layer()->last_transaction()) {
+    EXPECT_EQ(net::LOW,
+              cache.network_layer()->last_create_transaction_priority());
+    EXPECT_EQ(net::HIGHEST,
+              cache.network_layer()->last_transaction()->priority());
+  }
 
   EXPECT_EQ(net::OK, callback.WaitForResult());
 }