Removes mouse listeners from UserInputMonitor.

media/base/BUILD.gn

Index: media/base/BUILD.gn
diff --git a/media/base/BUILD.gn b/media/base/BUILD.gn
index 509a8d1e4622dbaaafb29ccb6a5b84cb8f72a296..80efe056e765410b517919a3c1219b008822c91e 100644
--- a/media/base/BUILD.gn
+++ b/media/base/BUILD.gn
@@ -450,7 +450,6 @@ source_set("unit_tests") {
     "text_ranges_unittest.cc",
     "text_renderer_unittest.cc",
     "time_delta_interpolator_unittest.cc",
-    "user_input_monitor_unittest.cc",
     "vector_math_unittest.cc",
     "video_codecs_unittest.cc",
     "video_decoder_config_unittest.cc",
@@ -495,6 +494,9 @@ source_set("unit_tests") {
   if (current_cpu == "x86" || current_cpu == "x64") {
     sources += [ "simd/convert_rgb_to_yuv_unittest.cc" ]
   }
+  if (is_linux || is_win) {
+    sources += [ "keyboard_event_counter_unittest.cc" ]
+  }
 }
 
 test("media_base_unittests") {