enable -Wstring-conversion when compiling with clang

chrome/browser/renderer_host/web_cache_manager_unittest.cc

 // 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.
 
 #include <string>
 
 #include "base/message_loop.h"
 #include "chrome/browser/renderer_host/web_cache_manager.h"
 #include "content/public/test/test_browser_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 238 matching lines @@
                             &strategy));
   EXPECT_EQ(2U, strategy.size());
 
   AllocationStrategy::iterator iter = strategy.begin();
   while (iter != strategy.end()) {
     if (iter->first == kRendererID)
       EXPECT_LE(kStats.liveSize + kStats.deadSize, iter->second);
     else if (iter->first == kRendererID2)
       EXPECT_LE(kStats2.liveSize, iter->second);
     else
-      EXPECT_FALSE("Unexpected entry in strategy");
+      ADD_FAILURE();   // Unexpected entry in strategy.
     ++iter;
   }
 
   manager()->Remove(kRendererID);
   manager()->Remove(kRendererID2);
 }
 
 TEST_F(WebCacheManagerTest, AddToStrategyTest) {
   manager()->Add(kRendererID);
   manager()->Add(kRendererID2);
@@ skipping 19 matching lines @@
   size_t total_bytes = 0;
   AllocationStrategy::iterator iter = strategy.begin();
   while (iter != strategy.end()) {
     total_bytes += iter->second;
 
     if (iter->first == kRendererID)
       EXPECT_LE(kStats.liveSize + kStats.deadSize, iter->second);
     else if (iter->first == kRendererID2)
       EXPECT_LE(kStats2.liveSize + kStats2.deadSize, iter->second);
     else
-      EXPECT_FALSE("Unexpected entry in strategy");
+      ADD_FAILURE();  // Unexpected entry in strategy.
     ++iter;
   }
 
   size_t expected_total_bytes = kExtraBytesToAllocate +
                                 kStats.liveSize + kStats.deadSize +
                                 kStats2.liveSize + kStats2.deadSize;
 
   EXPECT_GE(expected_total_bytes, total_bytes);
 
   manager()->Remove(kRendererID);
   manager()->Remove(kRendererID2);
 }