Extract FakeInputDispatcherPolicy into a separate cpp file

It will be used by other tests that will be added in the future.

Bug: 210460522
Test: build
Change-Id: I36d6b5aef98e621d8193d72063e8c7ecddd567a3
diff --git a/services/inputflinger/tests/Android.bp b/services/inputflinger/tests/Android.bp
index 09ae6dd..d389a0a 100644
--- a/services/inputflinger/tests/Android.bp
+++ b/services/inputflinger/tests/Android.bp
@@ -22,6 +22,14 @@
     default_applicable_licenses: ["frameworks_native_license"],
 }
 
+// Source files shared with InputDispatcher's benchmarks and fuzzers
+filegroup {
+    name: "inputdispatcher_common_test_sources",
+    srcs: [
+        "FakeInputDispatcherPolicy.cpp",
+    ],
+}
+
 cc_test {
     name: "inputflinger_tests",
     host_supported: true,
@@ -38,6 +46,7 @@
         "libinputflinger_defaults",
     ],
     srcs: [
+        ":inputdispatcher_common_test_sources",
         "AnrTracker_test.cpp",
         "CapturedTouchpadEventConverter_test.cpp",
         "CursorInputMapper_test.cpp",