GN: Don't compile battor_agent, imagediff, bitmaptools on Android

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 76c24b996e883c784bd135a23bf073e441b08825..d8055d11bcfbe148a1f7852d4447c47b16944753 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -196,7 +196,6 @@ group("both_gn_and_gyp") {
       "//third_party/mojo/src/mojo/edk/test:mojo_public_system_unittests",
       "//third_party/mojo/src/mojo/edk/test:mojo_public_utility_unittests",
       "//third_party/smhasher:pmurhash",
-      "//tools/battor_agent",
       "//tools/imagediff($host_toolchain)",
       "//tools/telemetry:bitmaptools($host_toolchain)",
       "//ui/display:display_unittests",
@@ -224,6 +223,10 @@ group("both_gn_and_gyp") {
     }
   }
 
+  if (is_mac || is_win || is_linux) {
+    deps += [ "//tools/battor_agent" ]
+  }
+
   deps += root_extra_deps
 
   if (enable_extensions) {