Fix bug entering text into table cell using IME

My CL https://chromium-review.googlesource.com/801979 exposed a bug with
PlainTextRange::CreateRange() when passed a collapsed range at the beginning of
a table cell. TextIterator outputs a tab character ('\t') when iterating over a
table cell boundary; PlainTextRange() is currently counting the tab character
in its character count for this case, but returning a start/end position
(they're the same since it's a collapsed range) before the <td> element, causing
an off-by-one error.

xiaochengh@ found a fix for this issue, so CreateRange() now returns a position
inside the text node, instead of before the <td> element.

Bug: 826615
Change-Id: Ief427ea6aeb0b93cf82bae3b6901cf1b2a8cb4c7
Reviewed-on: https://chromium-review.googlesource.com/987385Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Ryan Landay <rlanday@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547447}

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

@@ -339,6 +339,7 @@ jumbo_source_set("unit_tests") {
     "LayoutSelectionTest.cpp",
     "LocalCaretRectBiDiTest.cpp",
     "LocalCaretRectTest.cpp",
+    "PlainTextRangeTest.cpp",
     "PositionIteratorTest.cpp",
     "PositionTest.cpp",
     "PositionWithAffinityTest.cpp",

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

@@ -121,8 +121,8 @@ EphemeralRange PlainTextRange::CreateRangeFor(
       // FIXME: This is a workaround for the fact that the end of a run
       // is often at the wrong position for emitted '\n's or if the
       // layoutObject of the current node is a replaced element.
-      if (len == 1 &&
-          (it.CharacterAt(0) == '\n' || it.IsInsideAtomicInlineElement())) {
+      if (len == 1 && (it.CharacterAt(0) == '\n' || it.CharacterAt(0) == '\t' ||
+                       it.IsInsideAtomicInlineElement())) {
         it.Advance();
         if (!it.AtEnd()) {
           text_run_end_position = it.StartPositionInCurrentContainer();

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

+// Copyright 2018 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/PlainTextRange.h"
+
+#include "core/editing/EphemeralRange.h"
+#include "core/editing/testing/EditingTestBase.h"
+
+namespace blink {
+
+class PlainTextRangeTest : public EditingTestBase {
+ protected:
+  Element* InsertHTMLElement(const char* element_code, const char* element_id);
+};
+
+TEST_F(PlainTextRangeTest, RangeContainingTableCellBoundary) {
+  SetBodyInnerHTML(
+      "<table id='sample' contenteditable><tr><td>a</td><td "
+      "id='td2'>b</td></tr></table>");
+  Element* table = GetElementById("sample");
+
+  PlainTextRange plain_text_range(2, 2);
+  const EphemeralRange& range = plain_text_range.CreateRange(*table);
+  EXPECT_EQ(
+      "<table contenteditable id=\"sample\"><tbody><tr><td>a</td><td "
+      "id=\"td2\">|b</td></tr></tbody></table>",
+      GetCaretTextFromBody(range.StartPosition()));
+  EXPECT_TRUE(range.IsCollapsed());
+}
+
+}  // namespace blink

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

@@ -7,6 +7,7 @@
 #include <memory>
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
+#include "core/dom/NodeList.h"
 #include "core/dom/Range.h"
 #include "core/editing/Editor.h"
 #include "core/editing/EphemeralRange.h"
@@ -3208,4 +3209,26 @@ TEST_F(InputMethodControllerTest, SetCompositionAfterNonEditableElement) {
               .Build()));
 }
 
+TEST_F(InputMethodControllerTest, SetCompositionInTableCell) {
+  GetFrame().Selection().SetSelection(
+      SetSelectionTextToBody(
+          "<table id='sample' contenteditable><tr><td>a</td><td "
+          "id='td2'>|</td></tr></table>"),
+      SetSelectionOptions());
+  Element* const table = GetDocument().getElementById("sample");
+  table->focus();
+
+  Controller().SetComposition(String::FromUTF8("c"), Vector<ImeTextSpan>(), 1,
+                              1);
+
+  Element* const td2 = GetDocument().getElementById("td2");
+  const Node* const text_node = td2->firstChild();
+
+  Range* range = GetCompositionRange();
+  EXPECT_EQ(text_node, range->startContainer());
+  EXPECT_EQ(0u, range->startOffset());
+  EXPECT_EQ(text_node, range->endContainer());
+  EXPECT_EQ(1u, range->endOffset());
+}
+
 }  // namespace blink