Move wrapPassthroughInternal out of headers.

Move implementation of wrapPassthroughInternal into
sources. Still provide a templated version for
convenient use (which should be optimized out
when not used).

This function:
- isn't template specific
- duplication takes up space on device/in-memory

Test: hidl's run_all_device_tests.sh
Bug: 33754152
Change-Id: I9e949f953732d843053ac5d6655700d48eda3190
diff --git a/transport/HidlPassthroughSupport.cpp b/transport/HidlPassthroughSupport.cpp
new file mode 100644
index 0000000..e101e27
--- /dev/null
+++ b/transport/HidlPassthroughSupport.cpp
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <hidl/HidlPassthroughSupport.h>
+
+#include <hidl/HidlTransportUtils.h>
+#include <hidl/Static.h>
+
+using ::android::hidl::base::V1_0::IBase;
+
+namespace android {
+namespace hardware {
+namespace details {
+
+sp<IBase> wrapPassthroughInternal(sp<IBase> iface) {
+    if (iface == nullptr || iface->isRemote()) {
+        // doesn't know how to handle it.
+        return iface;
+    }
+    std::string myDescriptor = getDescriptor(iface.get());
+    if (myDescriptor.empty()) {
+        // interfaceDescriptor fails
+        return nullptr;
+    }
+    auto func = gBsConstructorMap.get(myDescriptor, nullptr);
+    if (!func) {
+        return nullptr;
+    }
+
+    sp<IBase> base = func(static_cast<void*>(iface.get()));
+
+    // To ensure this is an instance of IType, we would normally
+    // call castFrom, but gBsConstructorMap guarantees that its
+    // result is of the appropriate type (not necessaryly BsType,
+    // but definitely a child of IType).
+    return base;
+}
+
+}  // namespace details
+}  // namespace hardware
+}  // namespace android
\ No newline at end of file