adb: fdevent: move CheckMainThread logic to fdevent_context.

Test: adb_test
Change-Id: I10b93293af22d54ec739dc0f95c95df3ab082fb6
diff --git a/adb/fdevent/fdevent.cpp b/adb/fdevent/fdevent.cpp
index d6e3a66..698b293 100644
--- a/adb/fdevent/fdevent.cpp
+++ b/adb/fdevent/fdevent.cpp
@@ -20,7 +20,9 @@
 
 #include <inttypes.h>
 
+#include <android-base/logging.h>
 #include <android-base/stringprintf.h>
+#include <android-base/threads.h>
 
 #include "fdevent.h"
 #include "fdevent_poll.h"
@@ -46,6 +48,12 @@
                                        state.c_str());
 }
 
+void fdevent_context::CheckMainThread() {
+    if (main_thread_id_) {
+        CHECK_EQ(*main_thread_id_, android::base::GetThreadId());
+    }
+}
+
 void fdevent_context::Run(std::function<void()> fn) {
     {
         std::lock_guard<std::mutex> lock(run_queue_mutex_);