Get rid of unused parameter TextAffinity from TrailingWhitespacePosition()

This patch gets rid of unused parameter |TextAffinity| from
|TrailingWhitespacePosition()| for improving code health.

This patch is a preparation of renaming |VP_DEFAULT_AFFINITY| to
|TextAffinity::kDefault|.

Bug: 657237
Change-Id: I0c354cbbbe09afc757d23c23db0c8df244c6b09a
Reviewed-on: https://chromium-review.googlesource.com/701904Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506943}

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

@@ -1687,7 +1687,6 @@ Position LeadingWhitespacePosition(const Position& position,
 
 // This assumes that it starts in editable content.
 Position TrailingWhitespacePosition(const Position& position,
-                                    TextAffinity,
                                     WhitespacePositionOption option) {
   DCHECK(!NeedsLayoutTreeUpdate(position));
   DCHECK(IsEditablePosition(position)) << position;

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

@@ -304,9 +304,11 @@ Position LeadingWhitespacePosition(
     const Position&,
     TextAffinity,
     WhitespacePositionOption = kNotConsiderNonCollapsibleWhitespace);
+
+// TDOO(editing-dev): We should move |TrailingWhitespacePosition()| to
+// "DeleteSelection.cpp" since it is used only in "DeleteSelection.cpp".
 Position TrailingWhitespacePosition(
     const Position&,
-    TextAffinity,
     WhitespacePositionOption = kNotConsiderNonCollapsibleWhitespace);
 unsigned NumEnclosingMailBlockquotes(const Position&);
 PositionWithAffinity PositionRespectingEditingBoundary(

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

@@ -302,8 +302,7 @@ void DeleteSelectionCommand::InitializePositionData(
   // to the selection
   leading_whitespace_ = LeadingWhitespacePosition(
       upstream_start_, selection_to_delete_.Affinity());
-  trailing_whitespace_ =
-      TrailingWhitespacePosition(downstream_end_, VP_DEFAULT_AFFINITY);
+  trailing_whitespace_ = TrailingWhitespacePosition(downstream_end_);
 
   if (smart_delete_) {
     // skip smart delete if the selection to delete already starts or ends with
@@ -312,8 +311,7 @@ void DeleteSelectionCommand::InitializePositionData(
         CreateVisiblePosition(upstream_start_, selection_to_delete_.Affinity())
             .DeepEquivalent();
     bool skip_smart_delete =
-        TrailingWhitespacePosition(pos, VP_DEFAULT_AFFINITY,
-                                   kConsiderNonCollapsibleWhitespace)
+        TrailingWhitespacePosition(pos, kConsiderNonCollapsibleWhitespace)
             .IsNotNull();
     if (!skip_smart_delete)
       skip_smart_delete =
@@ -345,7 +343,7 @@ void DeleteSelectionCommand::InitializePositionData(
     // leading whitespace, as in the case where you double-click the first word
     // of a paragraph.
     if (!skip_smart_delete && !has_leading_whitespace_before_adjustment &&
-        TrailingWhitespacePosition(downstream_end_, VP_DEFAULT_AFFINITY,
+        TrailingWhitespacePosition(downstream_end_,
                                    kConsiderNonCollapsibleWhitespace)
             .IsNotNull()) {
       // Expand out one character downstream for smart delete and recalculate
@@ -355,8 +353,7 @@ void DeleteSelectionCommand::InitializePositionData(
                 .DeepEquivalent();
       upstream_end_ = MostBackwardCaretPosition(pos);
       downstream_end_ = MostForwardCaretPosition(pos);
-      trailing_whitespace_ =
-          TrailingWhitespacePosition(downstream_end_, VP_DEFAULT_AFFINITY);
+      trailing_whitespace_ = TrailingWhitespacePosition(downstream_end_);
 
       SetStartingSelectionOnSmartDelete(downstream_start_, downstream_end_);
     }