Add a const overload to DownloadItem::GetExternalData()

content/browser/download/download_item_impl_unittest.cc

 // Copyright (c) 2012 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/message_loop.h"
 #include "base/stl_util.h"
 #include "base/threading/thread.h"
 #include "content/browser/download/download_create_info.h"
 #include "content/browser/download/download_item_impl.h"
 #include "content/browser/download/download_request_handle.h"
@@ skipping 276 matching lines @@
 class TestExternalData : public DownloadItem::ExternalData {
  public:
   int value;
   virtual ~TestExternalData() {
     destructor_called++;
   }
 };
 
 TEST_F(DownloadItemTest, ExternalData) {
   DownloadItem* item = CreateDownloadItem(DownloadItem::IN_PROGRESS);
+  const DownloadItem* const_item = item;
 
   // Shouldn't be anything there before set.
   EXPECT_EQ(NULL, item->GetExternalData(&external_data_test_string));
+  EXPECT_EQ(NULL, const_item->GetExternalData(&external_data_test_string));
 
   TestExternalData* test1(new TestExternalData());
   test1->value = 2;
 
   // Should be able to get back what you set.
   item->SetExternalData(&external_data_test_string, test1);
   TestExternalData* test_result =
       static_cast<TestExternalData*>(
           item->GetExternalData(&external_data_test_string));
   EXPECT_EQ(test1, test_result);
 
+  // Ditto for const lookup.
+  const TestExternalData* test_const_result =
+      static_cast<const TestExternalData*>(
+          const_item->GetExternalData(&external_data_test_string));
+  EXPECT_EQ(static_cast<const TestExternalData*>(test1),
+            test_const_result);
+
   // Destructor should be called if value overwritten.  New value
   // should then be retrievable.
   TestExternalData* test2(new TestExternalData());
   test2->value = 3;
   EXPECT_EQ(0, destructor_called);
   item->SetExternalData(&external_data_test_string, test2);
   EXPECT_EQ(1, destructor_called);
   EXPECT_EQ(static_cast<DownloadItem::ExternalData*>(test2),
             item->GetExternalData(&external_data_test_string));
 
@@ skipping 14 matching lines @@
   item->SetExternalData(&external_data_test_string, test3);
   EXPECT_EQ(static_cast<DownloadItem::ExternalData*>(test3),
             item->GetExternalData(&external_data_test_string));
   DestroyDownloadItem(item);
   EXPECT_EQ(3, destructor_called);
 }
 
 TEST(MockDownloadItem, Compiles) {
   MockDownloadItem mock_item;
 }