Send Android accessibility event when object location changes.

Note that the LOCATION_CHANGED event isn't explicitly handled, it just gets mapped to a WINDOW_CONTENT_CHANGED event on Android.

BUG=407871

Review URL: https://codereview.chromium.org/510513003

Cr-Commit-Position: refs/heads/master@{#292216}
diff --git a/content/browser/accessibility/browser_accessibility.h b/content/browser/accessibility/browser_accessibility.h
index 17f70ca..eeb940e79 100644
--- a/content/browser/accessibility/browser_accessibility.h
+++ b/content/browser/accessibility/browser_accessibility.h
@@ -65,7 +65,7 @@
   virtual bool IsNative() const;
 
   // Called when the location changed.
-  virtual void OnLocationChanged() const {}
+  virtual void OnLocationChanged() {}
 
   // Return true if this object is equal to or a descendant of |ancestor|.
   bool IsDescendantOf(BrowserAccessibility* ancestor);