Add the ability to override WebContentsBindingSet binders for testing

content/public/browser/web_contents_binding_set.h

 // 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_BINDING_SET_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_BINDING_SET_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents.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 WebContentsImpl;
 
 // Base class for something which owns a mojo::AssociatedBindingSet on behalf
 // of a WebContents. See WebContentsFrameBindingSet<T> below.
 class CONTENT_EXPORT WebContentsBindingSet {
- protected:
+ public:
   class CONTENT_EXPORT Binder {
    public:
     virtual ~Binder() {}
 
     virtual void OnRequestForFrame(
         RenderFrameHost* render_frame_host,
         mojo::ScopedInterfaceEndpointHandle handle);
   };
 
+  // Helper class which test code can use with SetBinderForTesting() in order
+  // to override interface binding behavior in tests. Once this is set on a
+  // WebContentsBindingSet via SetBinderForTesting (see below), it will live
+  // until either it is replaced or the WebContents is destroyed.
+  template <typename Interface>
+  class TestBinder : public Binder {

[jam, 2017/03/20 17:07:32]

can this be moved to content/public/test?

[Ken Rockot(use gerrit already), 2017/03/20 17:50:47]

Done

+   public:
+    ~TestBinder() override {}
+
+    // Call for every new incoming interface request for a frame.
+    virtual void BindRequest(
+        RenderFrameHost* render_frame_host,
+        mojo::AssociatedInterfaceRequest<Interface> request) = 0;
+
+   private:
+    // Binder:
+    void OnRequestForFrame(
+        RenderFrameHost* render_frame_host,
+        mojo::ScopedInterfaceEndpointHandle handle) override {
+      mojo::AssociatedInterfaceRequest<Interface> request;
+      request.Bind(std::move(handle));
+      BindRequest(render_frame_host, std::move(request));
+    }
+  };
+
+  template <typename Interface>
+  void SetBinderForTesting(std::unique_ptr<TestBinder<Interface>> binder) {
+    binder_for_testing_ = std::move(binder);
+  }
+
+ protected:
   WebContentsBindingSet(WebContents* web_contents,
                         const std::string& interface_name,
                         std::unique_ptr<Binder> binder);
   ~WebContentsBindingSet();
 
  private:
   friend class WebContentsImpl;
 
   void CloseAllBindings();
   void OnRequestForFrame(RenderFrameHost* render_frame_host,
                          mojo::ScopedInterfaceEndpointHandle handle);
 
   const base::Closure remove_callback_;
   std::unique_ptr<Binder> binder_;
+  std::unique_ptr<Binder> binder_for_testing_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsBindingSet);
 };
 
 // Owns a set of Channel-associated interface bindings with frame context on
 // message dispatch.
 //
 // To use this, a |mojom::Foo| implementation need only own an instance of
 // WebContentsFrameBindingSet<mojom::Foo>. This allows remote RenderFrames to
 // acquire handles to the |mojom::Foo| interface via
@@ skipping 85 matching lines @@
   }
 
   RenderFrameHost* current_target_frame_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsFrameBindingSet);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_BINDING_SET_H_