Add conversion rule for aria-grabbed attributes.

content/browser/accessibility/browser_accessibility_cocoa.mm

Index: content/browser/accessibility/browser_accessibility_cocoa.mm
diff --git a/content/browser/accessibility/browser_accessibility_cocoa.mm b/content/browser/accessibility/browser_accessibility_cocoa.mm
index dd3daeb708ae7ca53fee6594de7b3bf4c8c34c11..1c940d4b0f9a0ed4dd33dd1d25c52d6c96163ccf 100644
--- a/content/browser/accessibility/browser_accessibility_cocoa.mm
+++ b/content/browser/accessibility/browser_accessibility_cocoa.mm
@@ -109,6 +109,7 @@ NSDictionary* attributeToMethodNameMap = nil;
     { @"AXARIABusy", @"ariaBusy" },
     { @"AXARIALive", @"ariaLive" },
     { @"AXARIARelevant", @"ariaRelevant" },
+    { @"AXGrabbed", @"grabbed" },
     { @"AXInvalid", @"invalid" },
     { @"AXLoaded", @"loaded" },
     { @"AXLoadingProgress", @"loadingProgress" },
@@ -343,6 +344,11 @@ NSDictionary* attributeToMethodNameMap = nil;
   return ret;
 }
 
+- (NSNumber*)grabbed {
+  bool boolValue = browserAccessibility_->GetBoolAttribute(ui::AX_ATTR_GRABBED);
+  return [NSNumber numberWithBool:boolValue];
+}
+
 - (id)header {
   int headerElementId = -1;
   if ([self internalRole] == ui::AX_ROLE_TABLE ||
@@ -1381,6 +1387,12 @@ NSDictionary* attributeToMethodNameMap = nil;
         @"AXARIABusy",
         nil]];
   }
+  //Add aria-grabbed attribute only if it has true.
+  if (browserAccessibility_->HasBoolAttribute(ui::AX_ATTR_GRABBED)) {
+    [ret addObjectsFromArray:[NSArray arrayWithObjects:
+        @"AXGrabbed",
+        nil]];
+  }
 
   //Add expanded attribute only if it has expanded or collapsed state.
   if (GetState(browserAccessibility_, ui::AX_STATE_EXPANDED) ||