Devirtualize calls made on a mojo::InterfacePtr<T>

This patch devirtualizes calls to interface methods made through a
mojo::InterfacePtr<T> and mojo::AssociatedInterfacePtr<T> by making
get() and the -> and . operators return the proxy type directly and
marking the interface methods on the proxy as final.

The motivation of this change is performance and binary size. The non-
virtual call sites are slightly smaller but not enough to effect the
complete binary. Performance should be net-positive but as yet has not
been accurately measured.

Bug: None
Change-Id: I463bc32c1989853606d118f57ded5c9dd9f34e2f
Reviewed-on: https://chromium-review.googlesource.com/747884
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Yuzhu Shen <yzshen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#513030}

mojo/public/cpp/bindings/associated_interface_ptr.h

@@ -32,6 +32,7 @@ class AssociatedInterfacePtr {
  public:
   using InterfaceType = Interface;
   using PtrInfoType = AssociatedInterfacePtrInfo<Interface>;
+  using Proxy = typename Interface::Proxy_;
 
   // Constructs an unbound AssociatedInterfacePtr.
   AssociatedInterfacePtr() {}
@@ -79,11 +80,11 @@ class AssociatedInterfacePtr {
 
   bool is_bound() const { return internal_state_.is_bound(); }
 
-  Interface* get() const { return internal_state_.instance(); }
+  Proxy* get() const { return internal_state_.instance(); }
 
   // Functions like a pointer to Interface. Must already be bound.
-  Interface* operator->() const { return get(); }
-  Interface& operator*() const { return *get(); }
+  Proxy* operator->() const { return get(); }
+  Proxy& operator*() const { return *get(); }
 
   // Returns the version number of the interface that the remote side supports.
   uint32_t version() const { return internal_state_.version(); }

mojo/public/cpp/bindings/interface_ptr.h

@@ -39,6 +39,7 @@ class InterfacePtr {
  public:
   using InterfaceType = Interface;
   using PtrInfoType = InterfacePtrInfo<Interface>;
+  using Proxy = typename Interface::Proxy_;
 
   // Constructs an unbound InterfacePtr.
   InterfacePtr() {}
@@ -89,11 +90,11 @@ class InterfacePtr {
 
   // Returns a raw pointer to the local proxy. Caller does not take ownership.
   // Note that the local proxy is thread hostile, as stated above.
-  Interface* get() const { return internal_state_.instance(); }
+  Proxy* get() const { return internal_state_.instance(); }
 
   // Functions like a pointer to Interface. Must already be bound.
-  Interface* operator->() const { return get(); }
-  Interface& operator*() const { return *get(); }
+  Proxy* operator->() const { return get(); }
+  Proxy& operator*() const { return *get(); }
 
   // Returns the version number of the interface that the remote side supports.
   uint32_t version() const { return internal_state_.version(); }

mojo/public/cpp/bindings/lib/associated_interface_ptr_state.h

@@ -97,10 +97,12 @@ class MOJO_CPP_BINDINGS_EXPORT AssociatedInterfacePtrStateBase {
 template <typename Interface>
 class AssociatedInterfacePtrState : public AssociatedInterfacePtrStateBase {
  public:
+  using Proxy = typename Interface::Proxy_;
+
   AssociatedInterfacePtrState() {}
   ~AssociatedInterfacePtrState() = default;
 
-  Interface* instance() {
+  Proxy* instance() {
     // This will be null if the object is not bound.
     return proxy_.get();
   }
@@ -129,8 +131,6 @@ class AssociatedInterfacePtrState : public AssociatedInterfacePtrStateBase {
   }
 
  private:
-  using Proxy = typename Interface::Proxy_;
-
   std::unique_ptr<Proxy> proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(AssociatedInterfacePtrState);

mojo/public/cpp/bindings/lib/interface_ptr_state.h

@@ -104,10 +104,12 @@ class MOJO_CPP_BINDINGS_EXPORT InterfacePtrStateBase {
 template <typename Interface>
 class InterfacePtrState : public InterfacePtrStateBase {
  public:
+  using Proxy = typename Interface::Proxy_;
+
   InterfacePtrState() = default;
   ~InterfacePtrState() = default;
 
-  Interface* instance() {
+  Proxy* instance() {
     ConfigureProxyIfNecessary();
 
     // This will be null if the object is not bound.
@@ -192,8 +194,6 @@ class InterfacePtrState : public InterfacePtrStateBase {
   }
 
  private:
-  using Proxy = typename Interface::Proxy_;
-
   void ConfigureProxyIfNecessary() {
     // The proxy has been configured.
     if (proxy_) {

mojo/public/tools/bindings/generators/cpp_templates/interface_proxy_declaration.tmpl

@@ -6,9 +6,9 @@ class {{export_attribute}} {{interface.name}}Proxy
 
 {%- for method in interface.methods %}
 {%-   if method.sync %}
-  bool {{method.name}}({{interface_macros.declare_sync_method_params("", method)}}) override;
+  bool {{method.name}}({{interface_macros.declare_sync_method_params("", method)}}) final;
 {%-   endif %}
-  void {{method.name}}({{interface_macros.declare_request_params("", method, use_once_callback)}}) override;
+  void {{method.name}}({{interface_macros.declare_request_params("", method, use_once_callback)}}) final;
 {%- endfor %}
 
  private: