Implement support for special offset constants in IAccessibleText methods....

chrome/browser/accessibility/browser_accessibility_win.cc

Index: chrome/browser/accessibility/browser_accessibility_win.cc
===================================================================
--- chrome/browser/accessibility/browser_accessibility_win.cc	(revision 75254)
+++ chrome/browser/accessibility/browser_accessibility_win.cc	(working copy)
@@ -1223,9 +1223,15 @@
     LONG start_offset,
     LONG direction) {
   LONG text_size = static_cast<LONG>(text.size());
-  DCHECK(start_offset >= 0 && start_offset <= text_size);
   DCHECK(direction == 1 || direction == -1);

[Chris Guillory, 2011/02/18 01:37:11]

Nit: Can we keep these DCHECKs next to each other.

[dmazzoni, 2011/02/18 17:52:37]

Sure. I moved the start_offset DCHECK back up to the top and  tested that its
value is either bounded by the string length OR one of the special values.

 
+  if (start_offset == IA2_TEXT_OFFSET_LENGTH) {
+    start_offset = text_size;
+  } else if (start_offset == IA2_TEXT_OFFSET_CARET) {
+    get_caretOffset(&start_offset);
+  }
+  DCHECK(start_offset >= 0 && start_offset <= text_size);
+
   if (boundary == IA2_TEXT_BOUNDARY_CHAR) {
     if (direction == 1 && start_offset < text_size)
       return start_offset + 1;