content: convert accessibility notifications to observer usage

content/browser/renderer_host/render_view_host_impl.h

Index: content/browser/renderer_host/render_view_host_impl.h
diff --git a/content/browser/renderer_host/render_view_host_impl.h b/content/browser/renderer_host/render_view_host_impl.h
index 7d57852228eed7aa35d9390d22bdea8f6a2efc11..e167092fd08de1b74f3fe318279653af953bd0c0 100644
--- a/content/browser/renderer_host/render_view_host_impl.h
+++ b/content/browser/renderer_host/render_view_host_impl.h
@@ -422,6 +422,16 @@ class CONTENT_EXPORT RenderViewHostImpl
     return accessibility_tree_;
   }
 
+  // Add/remove accessibility callbacks (only for testing).
+  void AddAccessibilityLayoutCompleteCallbackForTesting(
+      const base::Closure& callback);
+  void RemoveAccessibilityLayoutCompleteCallbackForTesting(
+      const base::Closure& callback);
+  void AddAccessibilityLoadCompleteCallbackForTesting(
+      const base::Closure& callback);
+  void RemoveAccessibilityLoadCompleteCallbackForTesting(
+      const base::Closure& callback);
+
   bool is_waiting_for_unload_ack_for_testing() {
     return is_waiting_for_unload_ack_;
   }
@@ -652,6 +662,10 @@ class CONTENT_EXPORT RenderViewHostImpl
   // callbacks.
   std::map<int, JavascriptResultCallback> javascript_callbacks_;
 
+  // Accessibility callbacks.
+  std::vector<base::Closure> accessibility_layout_callbacks_;

[dmazzoni, 2013/02/12 16:00:52]

I can't imagine we'll ever need more than one callback for tests. Just one of
each type should be fine, and the current usage pattern where it's used only to
block until the callback occurs should be fine.

How about if the callback is just called once and then deleted? Change it to:

SetOneTimeAccessibilityLoadCompleteCallbackForTesting()

...with no vector needed, and no Remove method needed.

[jam, 2013/02/12 17:48:18]

+1

+  std::vector<base::Closure> accessibility_load_callbacks_;
+
   // True if the render view can be shut down suddenly.
   bool sudden_termination_allowed_;