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
diff --git a/adb/daemon/usb.cpp b/adb/daemon/usb.cpp
index 87937fb..7fff05a 100644
--- a/adb/daemon/usb.cpp
+++ b/adb/daemon/usb.cpp
@@ -45,19 +45,15 @@
 #include <android-base/properties.h>
 #include <android-base/thread_annotations.h>
 
-#include <adbd/usb.h>
-
 #include "adb_unique_fd.h"
 #include "adb_utils.h"
+#include "daemon/usb_ffs.h"
 #include "sysdeps/chrono.h"
 #include "transport.h"
 #include "types.h"
 
 using android::base::StringPrintf;
 
-// We can't find out whether we have support for AIO on ffs endpoints until we submit a read.
-static std::optional<bool> gFfsAioSupported;
-
 // Not all USB controllers support operations larger than 16k, so don't go above that.
 // Also, each submitted operation does an allocation in the kernel of that size, so we want to
 // minimize our queue depth while still maintaining a deep enough queue to keep the USB stack fed.
@@ -612,17 +608,10 @@
         block->pending = true;
         struct iocb* iocb = &block->control;
         if (io_submit(aio_context_.get(), 1, &iocb) != 1) {
-            if (errno == EINVAL && !gFfsAioSupported.has_value()) {
-                HandleError("failed to submit first read, AIO on FFS not supported");
-                gFfsAioSupported = false;
-                return false;
-            }
-
             HandleError(StringPrintf("failed to submit read: %s", strerror(errno)));
             return false;
         }
 
-        gFfsAioSupported = true;
         return true;
     }
 
@@ -741,17 +730,10 @@
     static constexpr int kInterruptionSignal = SIGUSR1;
 };
 
-void usb_init_legacy();
-
 static void usb_ffs_open_thread() {
     adb_thread_setname("usb ffs open");
 
     while (true) {
-        if (gFfsAioSupported.has_value() && !gFfsAioSupported.value()) {
-            LOG(INFO) << "failed to use nonblocking ffs, falling back to legacy";
-            return usb_init_legacy();
-        }
-
         unique_fd control;
         unique_fd bulk_out;
         unique_fd bulk_in;
@@ -773,13 +755,5 @@
 }
 
 void usb_init() {
-    bool use_nonblocking = android::base::GetBoolProperty(
-            "persist.adb.nonblocking_ffs",
-            android::base::GetBoolProperty("ro.adb.nonblocking_ffs", true));
-
-    if (use_nonblocking) {
-        std::thread(usb_ffs_open_thread).detach();
-    } else {
-        usb_init_legacy();
-    }
+    std::thread(usb_ffs_open_thread).detach();
 }