Add DCHECK to BrowserAccessibilityManager::Remove to detect undefined behavoir that may lead to a...

chrome/browser/accessibility/browser_accessibility_mac_unittest.mm

 // Copyright (c) 2011 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.
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/ui/cocoa/cocoa_test_helper.h"
@@ skipping 32 matching lines @@
 }
 
 @end
 
 
 class BrowserAccessibilityTest : public CocoaTest {
  public:
   virtual void SetUp() {
     CocoaTest::SetUp();
     WebAccessibility root;
+    root.id = 1000;
     root.location.set_width(500);
     root.location.set_height(100);
     root.role = WebAccessibility::ROLE_WEB_AREA;
     root.string_attributes[WebAccessibility::ATTR_HELP] =
         ASCIIToUTF16("HelpText");
 
     WebAccessibility child1;
+    child1.id = 1001;
     child1.name = ASCIIToUTF16("Child1");
     child1.location.set_width(250);
     child1.location.set_height(100);
     child1.role = WebAccessibility::ROLE_BUTTON;
 
     WebAccessibility child2;
+    child2.id = 1002;
     child2.location.set_x(250);
     child2.location.set_width(250);
     child2.location.set_height(100);
     child2.role = WebAccessibility::ROLE_HEADING;
 
     root.children.push_back(child1);
     root.children.push_back(child2);
 
     delegate_.reset([[MockAccessibilityDelegate alloc] init]);
     manager_.reset(
@@ skipping 39 matching lines @@
       accessibilityAttributeValue:NSAccessibilityHelpAttribute];
   EXPECT_NSEQ(@"HelpText", helpText);
 }
 
 // Test querying for an invalid attribute to ensure it doesn't crash.
 TEST_F(BrowserAccessibilityTest, InvalidAttributeTest) {
   NSString* shouldBeNil = [accessibility_
       accessibilityAttributeValue:@"NSAnInvalidAttribute"];
   EXPECT_TRUE(shouldBeNil == nil);
 }