  // Returns a text marker that points to the first character in the document that
  // can be selected with VoiceOver.
  - (id)startTextMarker {
-@@ -1686,6 +1699,7 @@ - (id)startTextMarker {
- 
-   return CreateTextMarker(*first_text_object, 0, ui::AX_TEXT_AFFINITY_UPSTREAM);
+@@ -1741,6 +1754,7 @@ - (id)startTextMarker {
+   AXPlatformPositionInstance position = root->CreatePositionAt(0);
+   return CreateTextMarker(position->CreatePositionAtStartOfAnchor());
  }
 +#endif
  
  // Returns a subrole based upon the role.
  - (NSString*) subrole {
-@@ -1958,10 +1972,12 @@ - (NSAttributedString*)attributedValueForRange:(NSRange)range {
+@@ -2013,10 +2027,12 @@ - (NSAttributedString*)attributedValueForRange:(NSRange)range {
    NSString* value = base::SysUTF16ToNSString(browserAccessibility_->GetValue());
    NSMutableAttributedString* attributedValue =
        [[[NSMutableAttributedString alloc] initWithString:value] autorelease];

   }
 
diff --git a/content/common/sandbox_mac.mm b/content/common/sandbox_mac.mm
index 5271dcd..ee16b5a 100644
--- a/content/common/sandbox_mac.mm
+++ b/content/common/sandbox_mac.mm
@@ -41,10 +41,12 @@
 #include "ui/base/layout.h"
 #include "ui/gl/init/gl_factory.h"
 

 
   if ([attribute isEqualToString:
       NSAccessibilityBoundsForRangeParameterizedAttribute]) {
@@ -2334,6 +2352,7 @@ - (id)accessibilityAttributeValue:(NSString*)attribute
     return nil;
   }
 
+#ifndef MAS_BUILD
   if ([attribute isEqualToString:
            NSAccessibilityLineTextMarkerRangeForTextMarkerParameterizedAttribute]) {
     AXPlatformPositionInstance position =
@@ -2411,6 +2430,7 @@ AXPlatformRange range(position->CreatePreviousLineStartPosition(),
 
     return @(child->GetIndexInParent());
   }
