Introduce BackwardCodePointStateMachine to traverse chars in code points

third_party/WebKit/Source/core/editing/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("editing") {
   split_count = 5
   sources = [
     "CaretDisplayItemClient.cpp",
@@ skipping 177 matching lines @@
     "spellcheck/IdleSpellCheckCallback.cpp",
     "spellcheck/IdleSpellCheckCallback.h",
     "spellcheck/SpellCheckRequester.cpp",
     "spellcheck/SpellCheckRequester.h",
     "spellcheck/SpellChecker.cpp",
     "spellcheck/SpellChecker.h",
     "spellcheck/TextCheckingParagraph.cpp",
     "spellcheck/TextCheckingParagraph.h",
     "state_machines/BackspaceStateMachine.cpp",
     "state_machines/BackspaceStateMachine.h",
+    "state_machines/BackwardCodePointStateMachine.cpp",
+    "state_machines/BackwardCodePointStateMachine.h",
     "state_machines/BackwardGraphemeBoundaryStateMachine.cpp",
     "state_machines/BackwardGraphemeBoundaryStateMachine.h",
     "state_machines/ForwardGraphemeBoundaryStateMachine.cpp",
     "state_machines/ForwardGraphemeBoundaryStateMachine.h",
     "state_machines/StateMachineUtil.cpp",
     "state_machines/StateMachineUtil.h",
     "state_machines/TextSegmentationMachineState.cpp",
     "state_machines/TextSegmentationMachineState.h",
   ]
 
@@ skipping 42 matching lines @@
     "iterators/CharacterIteratorTest.cpp",
     "iterators/ForwardsTextBufferTest.cpp",
     "iterators/SearchBufferTest.cpp",
     "iterators/SimplifiedBackwardsTextIteratorTest.cpp",
     "iterators/TextIteratorTest.cpp",
     "iterators/TextSearcherICUTest.cpp",
     "markers/DocumentMarkerControllerTest.cpp",
     "serializers/StyledMarkupSerializerTest.cpp",
     "spellcheck/SpellCheckerTest.cpp",
     "state_machines/BackspaceStateMachineTest.cpp",
+    "state_machines/BackwardCodePointStateMachineTest.cpp",
     "state_machines/BackwardGraphemeBoundaryStateMachineTest.cpp",
     "state_machines/ForwardGraphemeBoundaryStateMachineTest.cpp",
     "state_machines/StateMachineTestUtil.cpp",
     "state_machines/StateMachineUtilTest.cpp",
   ]
 
   configs += [
     "//third_party/WebKit/Source/core:blink_core_pch",
     "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     "//testing/gmock",
     "//testing/gtest",
     "//third_party/WebKit/Source/core:core",
   ]
 }