Fixed word and line navigation in multi-line text fields.

ui/accessibility/ax_text_utils.cc

 // Copyright (c) 2011 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 "ui/accessibility/ax_text_utils.h"
 
 #include "base/logging.h"
 #include "base/strings/string_util.h"
 
 namespace ui {
 
+// line_breaks is a Misnomer. Blink provides the start offsets of each line
+// not the line breaks.
+// TODO(nektar): Rename line_breaks a11y attribute and variable references.
 size_t FindAccessibleTextBoundary(const base::string16& text,
                                   const std::vector<int>& line_breaks,
                                   TextBoundaryType boundary,
                                   size_t start_offset,
                                   TextBoundaryDirection direction) {
   size_t text_size = text.size();
-  DCHECK(start_offset <= text_size);
+  DCHECK_LE(start_offset, text_size);
 
   if (boundary == CHAR_BOUNDARY) {
     if (direction == FORWARDS_DIRECTION && start_offset < text_size)
       return start_offset + 1;
     else
       return start_offset;
   } else if (boundary == LINE_BOUNDARY) {
     if (direction == FORWARDS_DIRECTION) {
       for (size_t j = 0; j < line_breaks.size(); ++j) {
           size_t line_break = line_breaks[j] >= 0 ? line_breaks[j] : 0;
         if (line_break > start_offset)
           return line_break;
       }
       return text_size;
     } else {
       for (size_t j = line_breaks.size(); j != 0; --j) {
         size_t line_break = line_breaks[j - 1] >= 0 ? line_breaks[j - 1] : 0;
-        if (line_break < start_offset)
+        if (line_break <= start_offset)
           return line_break;
       }
       return 0;
     }
   }
 
   size_t result = start_offset;
   for (;;) {
     size_t pos;
     if (direction == FORWARDS_DIRECTION) {
@@ skipping 32 matching lines @@
 
     if (direction == FORWARDS_DIRECTION) {
       result++;
     } else {
       result--;
     }
   }
 }
 
 }  // Namespace ui