Cache accessibility description rather than returning temporary.

content/browser/accessibility/browser_accessibility_gtk.h

Index: content/browser/accessibility/browser_accessibility_gtk.h
diff --git a/content/browser/accessibility/browser_accessibility_gtk.h b/content/browser/accessibility/browser_accessibility_gtk.h
index 15dc88e177a3a71dd982c469ce4adb5df6c05081..088275b551d931259c7c2a9650349e7b0803b658 100644
--- a/content/browser/accessibility/browser_accessibility_gtk.h
+++ b/content/browser/accessibility/browser_accessibility_gtk.h
@@ -71,6 +71,7 @@ class BrowserAccessibilityGtk : public BrowserAccessibility {
 
   AtkRole atk_role() { return atk_role_; }
   const std::string& atk_acc_name() { return atk_acc_name_; }
+  const std::string& atk_acc_description() { return atk_acc_description_; }
 
   // BrowserAccessibility methods.
   virtual void PreInitialize() OVERRIDE;
@@ -85,6 +86,7 @@ class BrowserAccessibilityGtk : public BrowserAccessibility {
   AtkObject* atk_object_;
   AtkRole atk_role_;
   std::string atk_acc_name_;
+  std::string atk_acc_description_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityGtk);