Remove many unused files from //skia/ext

ui/android/BUILD.gn

 import("//build/config/android/rules.gni")
 
 assert(is_android)
 
-java_cpp_enum("java_enums_srcjar") {
-  sources = [
-    "../gfx/android/java_bitmap.h",
-  ]
-  outputs = [
-    "org/chromium/ui/gfx/BitmapFormat.java",
-  ]
-}
-
 java_strings_grd("ui_strings_grd") {
   grd_file = "java/strings/android_ui_strings.grd"
   outputs = [
     "values-am/android_ui_strings.xml",
     "values-ar/android_ui_strings.xml",
     "values-bg/android_ui_strings.xml",
     "values-ca/android_ui_strings.xml",
     "values-cs/android_ui_strings.xml",
     "values-da/android_ui_strings.xml",
     "values-de/android_ui_strings.xml",
@@ skipping 46 matching lines @@
 }
 
 android_library("ui_java") {
   DEPRECATED_java_in_dir = "java/src"
   deps = [
     ":ui_java_resources",
     "//base:base_java",
   ]
   srcjar_deps = [ ":java_enums_srcjar" ]
 }