Add AssertNoURLRequests() to URLRequestContext subclass destructors.

net/url_request/view_cache_helper_unittest.cc

Index: net/url_request/view_cache_helper_unittest.cc
diff --git a/net/url_request/view_cache_helper_unittest.cc b/net/url_request/view_cache_helper_unittest.cc
index 70bf201a507ee502dc60266055c2d2139ac693a1..31ad0ba872dfa0c7fc40934266b341a3c20e01a8 100644
--- a/net/url_request/view_cache_helper_unittest.cc
+++ b/net/url_request/view_cache_helper_unittest.cc
@@ -20,7 +20,10 @@ namespace {
 class TestURLRequestContext : public URLRequestContext {
  public:
   TestURLRequestContext();
-  virtual ~TestURLRequestContext() {}
+
+  virtual ~TestURLRequestContext() {
+    AssertNoURLRequests();
+  }
 
   // Gets a pointer to the cache backend.
   disk_cache::Backend* GetBackend();