[scenic][accessibility] Delete obsolete a11y_input system.

Design has changed, and this is no longer useful code.

SCN-1124 #comment

TEST=CQ

Change-Id: Ia19f4cdeb3a3f263bd022bd3efdf8a5a8b675d6b

garnet/bin/ui/scenic/BUILD.gn

@@ -39,10 +39,7 @@ executable("scenic") {
 
   if (enable_input_subsystem) {
     defines += [ "SCENIC_ENABLE_INPUT_SUBSYSTEM" ]
-    deps += [
-      "//garnet/lib/ui/a11y_input",
-      "//garnet/lib/ui/input",
-    ]
+    deps += ["//garnet/lib/ui/input"]
   }
 
   # Extra stack needed to avoid crashes when loading vulkan validation layers

garnet/bin/ui/scenic/app.cc

@@ -17,7 +17,6 @@
 #endif
 
 #ifdef SCENIC_ENABLE_INPUT_SUBSYSTEM
-#include "garnet/lib/ui/a11y_input/a11y_input_system.h"
 #include "garnet/lib/ui/input/input_system.h"
 #endif
 
@@ -46,9 +45,6 @@ App::App(sys::ComponentContext* app_context, inspect::Node inspect_node,
 #ifdef SCENIC_ENABLE_GFX_SUBSYSTEM
   auto input = scenic_->RegisterSystem<input::InputSystem>(gfx);
   FXL_DCHECK(input);
-
-  auto a11y_input = scenic_->RegisterSystem<a11y_input::A11yInputSystem>(gfx);
-  FXL_DCHECK(a11y_input);
 #else
 #error InputSystem requires gfx::GfxSystem.
 #endif

garnet/lib/ui/a11y_input/BUILD.gn

-# Copyright 2019 The Fuchsia Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-source_set("a11y_input") {
-  sources = [
-    "a11y_input_system.cc",
-    "a11y_input_system.h",
-  ]
-
-  deps = [
-    "//garnet/lib/ui/scenic",
-    "//garnet/public/lib/inspect",
-  ]
-}

garnet/lib/ui/a11y_input/a11y_input_system.cc

-#include "a11y_input_system.h"
-
-namespace scenic_impl {
-namespace a11y_input {
-
-const char* A11yInputSystem::kName = "A11yInputSystem";
-
-A11yInputSystem::A11yInputSystem(SystemContext context,
-                                 bool initialized_after_construction)
-    : System(std::move(context), initialized_after_construction) {
-  FXL_LOG(INFO) << "Scenic accessibility input system started.";
-}
-
-CommandDispatcherUniquePtr A11yInputSystem::CreateCommandDispatcher(
-    CommandDispatcherContext context) {
-  return CommandDispatcherUniquePtr(/* command dispatcher */ nullptr,
-                                    /* custom deleter */ nullptr);
-}
-
-}  // namespace a11y_input
-}  // namespace scenic_impl

garnet/lib/ui/a11y_input/a11y_input_system.h

-#ifndef GARNET_LIB_UI_A11Y_INPUT_A11Y_INPUT_SYSTEM_H_
-#define GARNET_LIB_UI_A11Y_INPUT_A11Y_INPUT_SYSTEM_H_
-
-#include <memory>
-
-#include "garnet/lib/ui/scenic/system.h"
-
-namespace scenic_impl {
-namespace a11y_input {
-
-class A11yInputSystem : public System {
- public:
-  static constexpr TypeId kTypeId = kA11yInput;
-  static const char* kName;
-
-  explicit A11yInputSystem(SystemContext context,
-                           bool initialized_after_construction);
-  ~A11yInputSystem() override = default;
-
-  virtual CommandDispatcherUniquePtr CreateCommandDispatcher(
-      CommandDispatcherContext context) override;
-
- private:
-};
-}  // namespace a11y_input
-}  // namespace scenic_impl
-
-#endif  // GARNET_LIB_UI_A11Y_INPUT_A11Y_INPUT_SYSTEM_H_

garnet/lib/ui/scenic/system.h

@@ -122,8 +122,6 @@ inline System::TypeId SystemTypeForCmd(
     case fuchsia::ui::scenic::Command::Tag::kGfx:
       return System::TypeId::kGfx;
     case fuchsia::ui::scenic::Command::Tag::kInput:
-      // TODO(SCN-1124): Provide a way to route input to a11y_input here when
-      // applicable.
       return System::TypeId::kInput;
     case fuchsia::ui::scenic::Command::Tag::kVectorial:
       return System::TypeId::kVectorial;