Make InsertText command not to split SPAN element containing TAB character

Before this patch, "InsertText" command splits SPAN element containing TAB
character when inserting text into it.

For example:
Before: <span>&#9;a|c</span>
Command: insertText "B"
After: <span>&#9;a</span>B|<span>c</span>

This behavior is introduced by the patch[1], which replaces
"class=apple-tab-span" to "style=white-space:pre".

This patch changes |IsTabHTMLSpanElement()| to check "white-space:pre" CSS
property to make "InsertText" command not to split SPAN element containing
TAB character with "white-space: pre".


Note: "apple-tab-span" CSS class is MacOS specific feature[2]. On MacOS,
UITextView puts following HTML into pasteboard:

<style>.Apple-Tab-Span { white-space: pre; }</style>
<span class=Apple-Tab-Span>&#9;</span>

[1] http://crrev.com/2718543003 Remove EditingAppleTabSpan class handling
[2] https://www.cocoanetics.com/2013/06/apple-tab-span/

Bug: 741826
Change-Id: I42d8d388e306b613fbe8ffa614b9e974db254c22
Reviewed-on: https://chromium-review.googlesource.com/697044
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506683}

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

@@ -1559,12 +1559,14 @@ HTMLElement* CreateHTMLElement(Document& document, const QualifiedName& name) {
 }
 
 bool IsTabHTMLSpanElement(const Node* node) {
-  if (!IsHTMLSpanElement(node) || !node->firstChild())
+  if (!IsHTMLSpanElement(node))
     return false;
-  if (node->firstChild()->IsCharacterDataNode() &&
-      ToCharacterData(node->firstChild())->data().Contains('\t'))
-    return true;
-  return false;
+  const Node* const first_child = NodeTraversal::FirstChild(*node);
+  if (!first_child || !first_child->IsTextNode())
+    return false;
+  if (!ToText(first_child)->data().Contains('\t'))
+    return false;
+  return node->GetComputedStyle()->WhiteSpace() == EWhiteSpace::kPre;
 }
 
 bool IsTabHTMLSpanElementTextNode(const Node* node) {

third_party/WebKit/Source/core/editing/commands/InsertTextCommandTest.cpp

@@ -32,4 +32,75 @@ TEST_F(InsertTextCommandTest, WithTypingStyle) {
          "without applying typing style.";
 }
 
+// http://crbug.com/741826
+TEST_F(InsertTextCommandTest, InsertChar) {
+  Selection().SetSelection(
+      SetSelectionTextToBody("<p contenteditable><span>\ta|c</span></p>"));
+  GetDocument().execCommand("insertText", false, "B", ASSERT_NO_EXCEPTION);
+  EXPECT_EQ("<p contenteditable><span>\taB|c</span></p>",
+            GetSelectionTextFromBody(Selection().GetSelectionInDOMTree()))
+      << "We should not split Text node";
+}
+
+// http://crbug.com/741826
+TEST_F(InsertTextCommandTest, InsertCharToWhiteSpacePre) {
+  Selection().SetSelection(SetSelectionTextToBody(
+      "<p contenteditable><span style='white-space:pre'>\ta|c</span></p>"));
+  GetDocument().execCommand("insertText", false, "B", ASSERT_NO_EXCEPTION);
+  EXPECT_EQ(
+      "<p contenteditable>"
+      "<span style=\"white-space:pre\">\ta</span>"
+      "B|"
+      "<span style=\"white-space:pre\">c</span>"
+      "</p>",
+      GetSelectionTextFromBody(Selection().GetSelectionInDOMTree()))
+      << "This is a just record current behavior. We should not split SPAN.";
+}
+
+// http://crbug.com/741826
+TEST_F(InsertTextCommandTest, InsertSpace) {
+  Selection().SetSelection(
+      SetSelectionTextToBody("<p contenteditable><span>\ta|c</span></p>"));
+  GetDocument().execCommand("insertText", false, "  ", ASSERT_NO_EXCEPTION);
+  EXPECT_EQ("<p contenteditable><span>\ta\xC2\xA0 |c</span></p>",
+            GetSelectionTextFromBody(Selection().GetSelectionInDOMTree()))
+      << "We should insert U+0020 without splitting SPAN";
+}
+
+// http://crbug.com/741826
+TEST_F(InsertTextCommandTest, InsertSpaceToWhiteSpacePre) {
+  Selection().SetSelection(SetSelectionTextToBody(
+      "<p contenteditable><span style='white-space:pre'>\ta|c</span></p>"));
+  GetDocument().execCommand("insertText", false, "  ", ASSERT_NO_EXCEPTION);
+  EXPECT_EQ(
+      "<p contenteditable>"
+      "<span style=\"white-space:pre\">\ta</span>"
+      "\xC2\xA0\xC2\xA0|"
+      "<span style=\"white-space:pre\">c</span></p>",
+      GetSelectionTextFromBody(Selection().GetSelectionInDOMTree()))
+      << "We should insert U+0020 without splitting SPAN";
+}
+
+// http://crbug.com/741826
+TEST_F(InsertTextCommandTest, InsertTab) {
+  Selection().SetSelection(
+      SetSelectionTextToBody("<p contenteditable><span>\ta|c</span></p>"));
+  GetDocument().execCommand("insertText", false, "\t", ASSERT_NO_EXCEPTION);
+  EXPECT_EQ(
+      "<p contenteditable>"
+      "<span>\ta<span style=\"white-space:pre\">\t|</span>c</span>"
+      "</p>",
+      GetSelectionTextFromBody(Selection().GetSelectionInDOMTree()));
+}
+
+// http://crbug.com/741826
+TEST_F(InsertTextCommandTest, InsertTabToWhiteSpacePre) {
+  Selection().SetSelection(SetSelectionTextToBody(
+      "<p contenteditable><span style='white-space:pre'>\ta|c</span></p>"));
+  GetDocument().execCommand("insertText", false, "\t", ASSERT_NO_EXCEPTION);
+  EXPECT_EQ(
+      "<p contenteditable><span style=\"white-space:pre\">\ta\t|c</span></p>",
+      GetSelectionTextFromBody(Selection().GetSelectionInDOMTree()));
+}
+
 }  // namespace blink