Port most of the remainder of //tools/android from GYP to GN

tools/android/file_poller/BUILD.gn

Index: tools/android/file_poller/BUILD.gn
diff --git a/third_party/bspatch/BUILD.gn b/tools/android/file_poller/BUILD.gn
similarity index 77%
copy from third_party/bspatch/BUILD.gn
copy to tools/android/file_poller/BUILD.gn
index 39296159f8363a450d851a4ec824feb32038e963..828dc560dc9430b2aa957451af8e56e312bf2fa9 100644
--- a/third_party/bspatch/BUILD.gn
+++ b/tools/android/file_poller/BUILD.gn
@@ -2,16 +2,14 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("bspatch") {
+executable("file_poller") {
   sources = [
-    "mbspatch.cc",
-    "mbspatch.h",
+    "file_poller.cc",
+  ]
+  deps = [
+    "//base",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
-
-  deps = [
-    "//third_party/lzma_sdk",
-  ]
 }