Move character{After,Before}() for VisiblePosition to VisibleUnits.cpp

This patch moves |character{After,Before}()| for |VisiblePosition| to
"VisibleUnits.cpp" form "VisiblePosition.cpp" to make "VisiblePosition.cpp"
to simpler for improving code health and ease of templatizing |VisiblePosition|
class to introduce composed tree version.

This patch is a preparation of making selection to handle granularity for web
component, http://crrev.com/1277863002

BUG=513568

Review URL: https://codereview.chromium.org/1320233003

git-svn-id: svn://svn.chromium.org/blink/trunk@201519 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -590,31 +590,6 @@ VisiblePosition visiblePositionOf(const PositionInComposedTree& position, TextAf
     return VisiblePosition::createWithoutCanonicalization(PositionWithAffinity(toPositionInDOMTree(canonicalized.position()), canonicalized.affinity()));
 }
 
-UChar32 characterAfter(const VisiblePosition& visiblePosition)
-{
-    // We canonicalize to the first of two equivalent candidates, but the second
-    // of the two candidates is the one that will be inside the text node
-    // containing the character after this visible position.
-    Position pos = mostForwardCaretPosition(visiblePosition.deepEquivalent());
-    if (!pos.isOffsetInAnchor())
-        return 0;
-    Node* containerNode = pos.computeContainerNode();
-    if (!containerNode || !containerNode->isTextNode())
-        return 0;
-    unsigned offset = static_cast<unsigned>(pos.offsetInContainerNode());
-    Text* textNode = toText(containerNode);
-    unsigned length = textNode->length();
-    if (offset >= length)
-        return 0;
-
-    return textNode->data().characterStartingAt(offset);
-}
-
-UChar32 characterBefore(const VisiblePosition& visiblePosition)
-{
-    return characterAfter(previousPositionOf(visiblePosition));
-}
-
 IntRect absoluteCaretBoundsOf(const VisiblePosition& visiblePosition)
 {
     LayoutObject* layoutObject;

third_party/WebKit/Source/core/editing/VisiblePosition.h

@@ -131,11 +131,6 @@ VisiblePosition rightPositionOf(const VisiblePosition&);
 CORE_EXPORT Position canonicalPositionOf(const Position&);
 CORE_EXPORT PositionInComposedTree canonicalPositionOf(const PositionInComposedTree&);
 
-// TODO(yosin) We should move |characterAfter()| and |characterBefore()| to
-// "VisibleUnits.cpp"
-UChar32 characterAfter(const VisiblePosition&);
-UChar32 characterBefore(const VisiblePosition&);
-
 // TODO(yosin) We should move |honorEditingBoundaryAtOr{Before,After} to
 // "VisibleUnits.cpp" as static function.
 // next() and previous() will increment/decrement by a character cluster.

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

@@ -2359,6 +2359,31 @@ static VisiblePosition skipToEndOfEditingBoundary(const VisiblePosition& pos, co
     return firstEditableVisiblePositionAfterPositionInRoot(pos.deepEquivalent(), highestRoot);
 }
 
+UChar32 characterAfter(const VisiblePosition& visiblePosition)
+{
+    // We canonicalize to the first of two equivalent candidates, but the second
+    // of the two candidates is the one that will be inside the text node
+    // containing the character after this visible position.
+    Position pos = mostForwardCaretPosition(visiblePosition.deepEquivalent());
+    if (!pos.isOffsetInAnchor())
+        return 0;
+    Node* containerNode = pos.computeContainerNode();
+    if (!containerNode || !containerNode->isTextNode())
+        return 0;
+    unsigned offset = static_cast<unsigned>(pos.offsetInContainerNode());
+    Text* textNode = toText(containerNode);
+    unsigned length = textNode->length();
+    if (offset >= length)
+        return 0;
+
+    return textNode->data().characterStartingAt(offset);
+}
+
+UChar32 characterBefore(const VisiblePosition& visiblePosition)
+{
+    return characterAfter(previousPositionOf(visiblePosition));
+}
+
 VisiblePosition nextPositionOf(const VisiblePosition& visiblePosition, EditingBoundaryCrossingRule rule)
 {
     VisiblePosition next(nextVisuallyDistinctCandidate(visiblePosition.deepEquivalent()), visiblePosition.affinity());

third_party/WebKit/Source/core/editing/VisibleUnits.h

@@ -85,6 +85,9 @@ CORE_EXPORT PositionInComposedTree mostForwardCaretPosition(const PositionInComp
 CORE_EXPORT bool isVisuallyEquivalentCandidate(const Position&);
 CORE_EXPORT bool isVisuallyEquivalentCandidate(const PositionInComposedTree&);
 
+UChar32 characterAfter(const VisiblePosition&);
+UChar32 characterBefore(const VisiblePosition&);
+
 VisiblePosition nextPositionOf(const VisiblePosition&, EditingBoundaryCrossingRule = CanCrossEditingBoundary);
 VisiblePosition previousPositionOf(const VisiblePosition&, EditingBoundaryCrossingRule = CanCrossEditingBoundary);