Add AXTreeDelegate and refactor other AXTree classes slightly.

ui/accessibility/ax_generated_tree_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_number_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/accessibility/ax_node.h"
 #include "ui/accessibility/ax_serializable_tree.h"
 #include "ui/accessibility/ax_tree.h"
@@ skipping 189 matching lines @@
       SCOPED_TRACE("tree1 is " + TreeToString(tree0));
 
       // Now iterate over which node to update first, |k|.
       for (int k = 0; k < tree_size; k++) {
         SCOPED_TRACE("i=" + base::IntToString(i) +
                      " j=" + base::IntToString(j) +
                      " k=" + base::IntToString(k));
 
         // Start by serializing tree0 and unserializing it into a new
         // empty tree |dst_tree|.
-        scoped_ptr<AXTreeSource<AXNode> > tree0_source(
+        scoped_ptr<AXTreeSource<const AXNode*> > tree0_source(
             tree0.CreateTreeSource());
-        AXTreeSerializer<AXNode> serializer(tree0_source.get());
+        AXTreeSerializer<const AXNode*> serializer(tree0_source.get());
         AXTreeUpdate update0;
         serializer.SerializeChanges(tree0.GetRoot(), &update0);
 
         AXTree dst_tree;
         ASSERT_TRUE(dst_tree.Unserialize(update0));
 
         // At this point, |dst_tree| should now be identical to |tree0|.
         EXPECT_EQ(TreeToString(tree0), TreeToString(dst_tree));
 
         // Next, pretend that tree0 turned into tree1, and serialize
         // a sequence of updates to |dst_tree| to match.
-        scoped_ptr<AXTreeSource<AXNode> > tree1_source(
+        scoped_ptr<AXTreeSource<const AXNode*> > tree1_source(
             tree1.CreateTreeSource());
         serializer.ChangeTreeSourceForTesting(tree1_source.get());
 
         for (int k_index = 0; k_index < tree_size; ++k_index) {
           int id = 1 + (k + k_index) % tree_size;
           AXTreeUpdate update;
           serializer.SerializeChanges(tree1.GetFromId(id), &update);
           ASSERT_TRUE(dst_tree.Unserialize(update));
         }
 
         // After the sequence of updates, |dst_tree| should now be
         // identical to |tree1|.
         EXPECT_EQ(TreeToString(tree1), TreeToString(dst_tree));
       }
     }
   }
 }
 
 }  // namespace ui