Fix a bug when inputting text after grapheme cluster

third_party/WebKit/Source/core/editing/InputMethodControllerTest.cpp

 // Copyright 2014 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.
 
 #include "core/editing/InputMethodController.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/dom/Range.h"
 #include "core/editing/Editor.h"
@@ skipping 165 matching lines @@
 
   Range* range = controller().compositionRange();
   EXPECT_EQ(0, range->startOffset());
   EXPECT_EQ(5, range->endOffset());
 
   PlainTextRange plainTextRange(PlainTextRange::create(*div, *range));
   EXPECT_EQ(0u, plainTextRange.start());
   EXPECT_EQ(5u, plainTextRange.end());
 }
 
+TEST_F(InputMethodControllerTest, SetCompositionAfterEmoji) {
+  // "trophy" = U+1F3C6 = 0xF0 0x9F 0x8F 0x86 (UTF8).
+  Element* div = insertHTMLElement(
+      "<div id='sample' contenteditable>&#x1f3c6</div>", "sample");
+
+  Vector<CompositionUnderline> underlines;
+  underlines.push_back(CompositionUnderline(0, 2, Color(255, 0, 0), false, 0));
+
+  document().updateStyleAndLayout();
+  controller().setEditableSelectionOffsets(PlainTextRange(2, 2));
+  EXPECT_EQ(2, frame().selection().start().computeOffsetInContainerNode());
+  EXPECT_EQ(2, frame().selection().end().computeOffsetInContainerNode());
+
+  controller().setComposition(String("a"), underlines, 1, 1);
+  EXPECT_STREQ("\xF0\x9F\x8F\x86\x61", div->innerText().utf8().data());
+
+  controller().setComposition(String("ab"), underlines, 2, 2);
+  EXPECT_STREQ("\xF0\x9F\x8F\x86\x61\x62", div->innerText().utf8().data());
+}
+
 TEST_F(InputMethodControllerTest, SetCompositionKeepingStyle) {
   Element* div = insertHTMLElement(
       "<div id='sample' "
       "contenteditable>abc1<b>2</b>34567<b>8</b>9d<b>e</b>f</div>",
       "sample");
 
   Vector<CompositionUnderline> underlines;
   underlines.push_back(CompositionUnderline(3, 12, Color(255, 0, 0), false, 0));
   controller().setCompositionFromExistingText(underlines, 3, 12);
 
@@ skipping 997 matching lines @@
 
   controller().commitText(String("string"), underlines, 0);
 
   ASSERT_EQ(1u, document().markers().markers().size());
 
   EXPECT_EQ(9u, document().markers().markers()[0]->startOffset());
   EXPECT_EQ(15u, document().markers().markers()[0]->endOffset());
 }
 
 }  // namespace blink