adb: Remove most C-style allocations

This change gets rid of most malloc/calloc/free calls. The future is
now!

Bug: None
Test: test_device.py
Change-Id: Iccfe3bd4fe45a0319bd9f23b8cbff4c7070c9f4d
diff --git a/transport_test.cpp b/transport_test.cpp
index d987d4f..8c628d8 100644
--- a/transport_test.cpp
+++ b/transport_test.cpp
@@ -86,9 +86,9 @@
     ASSERT_EQ(0U, t.features().size());
     ASSERT_EQ(kCsHost, t.GetConnectionState());
 
-    ASSERT_EQ(nullptr, t.product);
-    ASSERT_EQ(nullptr, t.model);
-    ASSERT_EQ(nullptr, t.device);
+    ASSERT_EQ(std::string(), t.product);
+    ASSERT_EQ(std::string(), t.model);
+    ASSERT_EQ(std::string(), t.device);
 }
 
 TEST(transport, parse_banner_product_features) {