Move adbd's legacy USB implementation to fastboot.

This code path is effectively dead in adbd, and fastboot's dependency on
libadbd makes it hard to refactor adbd's dependencies.

Bug: http://b/150317254
Test: built and flashed aosp_walleye-eng
Change-Id: I5118136d32fdcbbd011559ed0a4a71e1dc7bf064
Merged-In: I5118136d32fdcbbd011559ed0a4a71e1dc7bf064
(cherry picked from commit 0871824de6c5b868f2a2e67c9b5673cb2181b4c6)
diff --git a/adb/client/usb.h b/adb/client/usb.h
new file mode 100644
index 0000000..b371788
--- /dev/null
+++ b/adb/client/usb.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#pragma once
+
+#include <sys/types.h>
+
+#include "adb.h"
+#include "transport.h"
+
+// USB host/client interface.
+
+#define ADB_USB_INTERFACE(handle_ref_type)                       \
+    void usb_init();                                             \
+    void usb_cleanup();                                          \
+    int usb_write(handle_ref_type h, const void* data, int len); \
+    int usb_read(handle_ref_type h, void* data, int len);        \
+    int usb_close(handle_ref_type h);                            \
+    void usb_reset(handle_ref_type h);                           \
+    void usb_kick(handle_ref_type h);                            \
+    size_t usb_get_max_packet_size(handle_ref_type)
+
+// Linux and Darwin clients have native and libusb implementations.
+
+namespace libusb {
+struct usb_handle;
+ADB_USB_INTERFACE(libusb::usb_handle*);
+}  // namespace libusb
+
+namespace native {
+struct usb_handle;
+ADB_USB_INTERFACE(native::usb_handle*);
+}  // namespace native
+
+// Empty base that both implementations' opaque handles inherit from.
+struct usb_handle {};
+
+ADB_USB_INTERFACE(::usb_handle*);
+
+// USB device detection.
+int is_adb_interface(int usb_class, int usb_subclass, int usb_protocol);
+
+bool should_use_libusb();
+
+struct UsbConnection : public BlockingConnection {
+    explicit UsbConnection(usb_handle* handle) : handle_(handle) {}
+    ~UsbConnection();
+
+    bool Read(apacket* packet) override final;
+    bool Write(apacket* packet) override final;
+    bool DoTlsHandshake(RSA* key, std::string* auth_key) override final;
+
+    void Close() override final;
+    virtual void Reset() override final;
+
+    usb_handle* handle_;
+};