Mojo C++ Bindings: Introduce mojo::SupportsStrongBinding

mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc

Index: mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc
diff --git a/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc b/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc
index 0a2f669597ccace6b3ec72d613d0fd28e8a73cd0..64f92933ebc546190a7504145b55dbb775fdeb37 100644
--- a/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc
+++ b/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc
@@ -480,7 +480,8 @@ TEST_F(InterfacePtrTest, RequireVersion) {
   EXPECT_EQ(456, impl.integer());
 }
 
-class StrongMathCalculatorImpl : public math::Calculator {
+class StrongMathCalculatorImpl
+    : public SupportsStrongBinding<math::Calculator> {
  public:
   StrongMathCalculatorImpl(bool* destroyed) : destroyed_(destroyed) {}
   ~StrongMathCalculatorImpl() override { *destroyed_ = true; }
@@ -613,7 +614,7 @@ TEST(WeakConnectorTest, Math) {
   EXPECT_FALSE(destroyed);
 }
 
-class CImpl : public C {
+class CImpl : public SupportsStrongBinding<C> {
  public:
   CImpl(bool* d_called, const base::Closure& closure)
       : d_called_(d_called), closure_(closure) {}
@@ -629,7 +630,7 @@ class CImpl : public C {
   base::Closure closure_;
 };
 
-class BImpl : public B {
+class BImpl : public SupportsStrongBinding<B> {
  public:
   BImpl(bool* d_called, const base::Closure& closure)
       : d_called_(d_called), closure_(closure) {}