Move ftrace_reader code into src/traced/probes/ftrace

Reduces the API surface hiding the ftrace reader into src/.

Change-Id: Ie89b90013c6bd22ceed8aaf9595a23a4185b7b92
diff --git a/Android.bp.extras b/Android.bp.extras
index daef82d..d64f3a9 100644
--- a/Android.bp.extras
+++ b/Android.bp.extras
@@ -4,12 +4,12 @@
   srcs: [
     "src/base/android_task_runner.cc",
     "src/base/test/test_task_runner.cc",
-    "src/ftrace_reader/cpu_reader.cc",
-    "src/ftrace_reader/event_info.cc",
-    "src/ftrace_reader/format_parser.cc",
-    "src/ftrace_reader/ftrace_controller.cc",
-    "src/ftrace_reader/ftrace_procfs.cc",
-    "src/ftrace_reader/proto_translation_table.cc",
+    "src/traced/probes/ftrace/cpu_reader.cc",
+    "src/traced/probes/ftrace/event_info.cc",
+    "src/traced/probes/ftrace/format_parser.cc",
+    "src/traced/probes/ftrace/ftrace_controller.cc",
+    "src/traced/probes/ftrace/ftrace_procfs.cc",
+    "src/traced/probes/ftrace/proto_translation_table.cc",
     "src/traced/probes/probes_producer.cc",
     "test/end_to_end_integrationtest.cc",
     "test/fake_producer.cc",