Adds routed interface support between RenderFrameHost and RenderFrame

content/public/browser/web_contents_interface_registry.h

Index: content/public/browser/web_contents_interface_registry.h
diff --git a/content/public/browser/web_contents_interface_registry.h b/content/public/browser/web_contents_interface_registry.h
new file mode 100644
index 0000000000000000000000000000000000000000..cc5a99fcc6106912350b104287cc4aaadefd45b4
--- /dev/null
+++ b/content/public/browser/web_contents_interface_registry.h
@@ -0,0 +1,127 @@
+// Copyright 2016 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.
+
+#ifndef CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_INTERFACE_REGISTRY_H_
+#define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_INTERFACE_REGISTRY_H_
+
+#include <map>
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "content/common/content_export.h"
+#include "mojo/public/cpp/bindings/associated_binding_set.h"
+#include "mojo/public/cpp/bindings/associated_interface_request.h"
+#include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
+
+namespace content {
+
+class RenderFrameHost;
+class WebContents;
+
+// A helper class to hold per-frame associated interface bindings for every
+// frame belonging to a single WebContents. Each WebContents owns a single
+// instance of this class.
+class CONTENT_EXPORT WebContentsInterfaceRegistry {
+ public:
+  virtual ~WebContentsInterfaceRegistry() {}
+
+  // Returns the RenderFrameHost targeted by the current binding dispatch. See
+  // AddFrameInterface() below for details.
+  virtual RenderFrameHost* GetCurrentTargetFrame() = 0;
+
+  virtual base::WeakPtr<WebContentsInterfaceRegistry> GetWeakPtr() = 0;
+
+  // Allows test code to control the target frame currently seen by calls to
+  // GetCurrentTargetFrame(). Useful when simulating incoming message calls.
+  virtual void SetCurrentTargetFrameForTesting(
+      RenderFrameHost* render_frame_host) = 0;
+
+  // Adds a new interface to the registry. A separate Interface binding is
+  // (lazily) established for every RenderFrameHost belonging to every
+  // WebContents the registry knows about.
+  //
+  // Incoming messages on Interface are routed to |impl|, and during the extent

[Sam McNally, 2016/09/09 05:33:15]

impl?

+  // of any message dispatch (i.e. any Interface call on |impl|), |impl| may
+  // call GetCurrentTargetFrame() above to get the RenderFrameHost whose
+  // specific binding was targeted by the message.
+  template <typename Interface>
+  void AddFrameInterface(Interface* iface) {

[Sam McNally, 2016/09/09 05:33:15]

What's wrong with interface?

+    AddFrameInterface(Interface::Name_,
+                      base::MakeUnique<FrameInterface<Interface>>(iface, this));
+  }
+
+  template <typename Interface>
+  void RemoveFrameInterface() { RemoveFrameInterface(Interface::Name_); }
+
+ protected:
+  class FrameInterfaceBase {
+   public:
+    virtual ~FrameInterfaceBase() {}
+
+    virtual void AddBinding(RenderFrameHost* render_frame_host,
+                            mojo::ScopedInterfaceEndpointHandle handle) = 0;
+    virtual void RemoveBinding(RenderFrameHost* render_frame_host) = 0;
+    virtual RenderFrameHost* GetCurrentTargetFrame() = 0;
+  };
+
+  // Generic helpers for the implementation to provide. See the templated
+  // AddFrameInterface and RemoveFrameInterface above.
+  virtual void AddFrameInterface(const std::string& name,
+                                 std::unique_ptr<FrameInterfaceBase> iface) = 0;
+  virtual void RemoveFrameInterface(const std::string& name) = 0;
+
+  // Called immediately before any message or error is dispatched on behalf of
+  // any owned bindings.
+  virtual void WillDispatchForFrame(RenderFrameHost* render_frame_host) = 0;
+
+  template <typename Interface>
+  class FrameInterface : public FrameInterfaceBase {
+   public:
+    FrameInterface(Interface* impl, WebContentsInterfaceRegistry* registry)
+        : impl_(impl), bindings_(mojo::BindingSetDispatchMode::WITH_CONTEXT) {
+      bindings_.set_pre_dispatch_handler(
+          base::Bind(&WebContentsInterfaceRegistry::WillDispatchForContext,
+                     base::Unretained(registry)));
+    }
+
+    ~FrameInterface() override {}
+
+    void AddBinding(RenderFrameHost* render_frame_host,
+                    mojo::ScopedInterfaceEndpointHandle handle) override {
+      mojo::AssociatedInterfaceRequest<Interface> request;
+      request.Bind(std::move(handle));
+      frame_binding_map_[render_frame_host].push_back(bindings_.AddBinding(
+          impl_, std::move(request), static_cast<void*>(render_frame_host)));
+    }
+
+    void RemoveBinding(RenderFrameHost* render_frame_host) override {
+      auto it = frame_binding_map_.find(render_frame_host);
+      DCHECK(it != frame_binding_map_.end());
+      for (auto id : it->second)
+        bindings_.RemoveBinding(id);
+      frame_binding_map_.erase(it);
+    }
+
+    RenderFrameHost* GetCurrentTargetFrame() override {
+      return static_cast<RenderFrameHost*>(bindings_.dispatch_context());
+    }
+
+   private:
+    Interface* const impl_;
+    mojo::AssociatedBindingSet<Interface> bindings_;
+    std::map<RenderFrameHost*, std::vector<mojo::BindingId>> frame_binding_map_;
+
+    DISALLOW_COPY_AND_ASSIGN(FrameInterface);
+  };
+
+ private:
+  void WillDispatchForContext(void* context) {
+    WillDispatchForFrame(reinterpret_cast<RenderFrameHost*>(context));
+  }
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_INTERFACE_REGISTRY_H_