Move iOS image_fetcher::ImageDecoder to layered component

ios/chrome/browser/suggestions/BUILD.gn

Index: ios/chrome/browser/suggestions/BUILD.gn
diff --git a/ios/chrome/browser/suggestions/BUILD.gn b/ios/chrome/browser/suggestions/BUILD.gn
index 7cf651ac6a827553d9cf08df08ccb142c94b6ed2..598ef9326e27c091784885110f2f62c73071399b 100644
--- a/ios/chrome/browser/suggestions/BUILD.gn
+++ b/ios/chrome/browser/suggestions/BUILD.gn
@@ -5,8 +5,6 @@
 source_set("suggestions") {
   configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
-    "ios_image_decoder_impl.h",
-    "ios_image_decoder_impl.mm",
     "suggestions_service_factory.h",
     "suggestions_service_factory.mm",
   ]
@@ -28,17 +26,3 @@ source_set("suggestions") {
     "//ui/gfx",
   ]
 }
-
-source_set("unit_tests") {
-  configs += [ "//build/config/compiler:enable_arc" ]
-  testonly = true
-  sources = [
-    "ios_image_decoder_impl_unittest.mm",
-  ]
-  deps = [
-    ":suggestions",
-    "//base",
-    "//testing/gtest",
-    "//ui/gfx",
-  ]
-}