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/BUILD.gn b/BUILD.gn
index 0cc344e..eda0304 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -94,11 +94,11 @@
 
   if (!build_with_chromium) {
     deps += [
-      "src/ftrace_reader:unittests",
       "src/ipc:unittests",
       "src/perfetto_cmd:unittests",
       "src/traced/probes:unittests",
       "src/traced/probes/filesystem:unittests",
+      "src/traced/probes/ftrace:unittests",
       "tools/ftrace_proto_gen:unittests",
       "tools/sanitizers_unittests",
     ]
@@ -113,7 +113,7 @@
     testonly = true
     deps = [
       "gn:default_deps",
-      "src/ftrace_reader:ftrace_reader_benchmarks",
+      "src/traced/probes/ftrace:benchmarks",
       "src/tracing:tracing_benchmarks",
       "test:benchmark_main",
       "test:end_to_end_benchmarks",
@@ -125,7 +125,7 @@
     deps = [
       "gn:default_deps",
       "gn:gtest_main",
-      "src/ftrace_reader:ftrace_reader_integrationtests",
+      "src/traced/probes/ftrace:integrationtests",
       "test:end_to_end_integrationtests",
     ]
     if (build_with_android) {
@@ -235,8 +235,8 @@
   group("fuzzers") {
     testonly = true
     deps = [
-      "src/ftrace_reader:cpu_reader_fuzzer",
       "src/ipc:buffered_frame_deserializer_fuzzer",
+      "src/traced/probes/ftrace:cpu_reader_fuzzer",
       "test:end_to_end_shared_memory_fuzzer",
     ]
   }