Add DCHECK to BrowserAccessibilityManager::Remove to detect undefined behavoir...

Add DCHECK to BrowserAccessibilityManager::Remove to detect undefined behavoir that may lead to a crash.
- Remove logic BrowserAccessibilityManagerTest.TestCreateEmptyDocument that attempts to change an accessibility object's role.

BUG=92716
Test=none
Review URL: http://codereview.chromium.org/7648055

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@97076 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/accessibility/browser_accessibility_manager_unittest.cc

@@ -604,7 +604,7 @@ TEST(BrowserAccessibilityManagerTest, TestCreateEmptyDocument) {
   tree2_1.role = WebAccessibility::ROLE_WEB_AREA;
 
   WebAccessibility tree2_2;
-  tree2_2.id = 1001;
+  tree2_2.id = 1002;
   tree2_2.role = WebAccessibility::ROLE_BUTTON;
 
   tree2_1.children.push_back(tree2_2);
@@ -614,17 +614,14 @@ TEST(BrowserAccessibilityManagerTest, TestCreateEmptyDocument) {
   // Fire another load complete.
   manager->OnAccessibilityNotifications(params);
 
-  BrowserAccessibility* acc2_2 = manager->GetFromRendererID(1001);
+  BrowserAccessibility* acc2_2 = manager->GetFromRendererID(1002);
 
   // Verify the root has not changed.
   EXPECT_EQ(root, manager->GetRoot());
 
-  // And the proper child remains.
+  // And the new child exists.
   EXPECT_EQ(WebAccessibility::ROLE_BUTTON, acc2_2->role());
-  EXPECT_EQ(1001, acc2_2->renderer_id());
-
-  // Verify we don't reuse objects that have changed roles.
-  EXPECT_NE(acc1_2, acc2_2);
+  EXPECT_EQ(1002, acc2_2->renderer_id());
 
   // Ensure we properly cleaned up.
   manager.reset();

content/browser/accessibility/browser_accessibility_manager.cc

@@ -116,6 +116,9 @@ BrowserAccessibility* BrowserAccessibilityManager::GetFromRendererID(
 
 void BrowserAccessibilityManager::Remove(int32 child_id, int32 renderer_id) {
   child_id_map_.erase(child_id);
+
+  // TODO(ctguil): Investigate if hit. We should never have a newer entry.
+  DCHECK(renderer_id_to_child_id_map_[renderer_id] == child_id);
   // Make sure we don't overwrite a newer entry (see UpdateNode for a possible
   // corner case).
   if (renderer_id_to_child_id_map_[renderer_id] == child_id)