Share the new adb USB diagnostic code with fastboot.

Bug: http://b/26134129
Change-Id: Ieaf0651c7b3f8a028760982091ec63a21a5484ba
diff --git a/adb/diagnose_usb.h b/adb/diagnose_usb.h
new file mode 100644
index 0000000..325b2e3
--- /dev/null
+++ b/adb/diagnose_usb.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef __DIAGNOSE_LINUX_USB_H
+#define __DIAGNOSE_LINUX_USB_H
+
+#include <string>
+
+// USB permission error help text. The short version will be one line, long may be multi-line.
+// Returns a string message to print, or an empty string if no problems could be found.
+std::string UsbNoPermissionsShortHelpText();
+std::string UsbNoPermissionsLongHelpText();
+
+#endif