Refactor Blink's ServiceConnector and add ability to mock in layout tests

content/renderer/mojo/blink_connector_impl.cc

Index: content/renderer/mojo/blink_connector_impl.cc
diff --git a/content/renderer/mojo/blink_connector_impl.cc b/content/renderer/mojo/blink_connector_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c2f8856ff58db998ef9d78f29522f7b582a21ef7
--- /dev/null
+++ b/content/renderer/mojo/blink_connector_impl.cc
@@ -0,0 +1,90 @@
+// Copyright 2017 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.
+
+#include "content/renderer/mojo/blink_connector_impl.h"
+
+#include <utility>
+
+#include "base/bind.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "services/service_manager/public/cpp/identity.h"
+#include "services/service_manager/public/cpp/interface_provider.h"
+
+namespace content {
+
+BlinkConnectorImpl::BlinkConnectorImpl(
+    std::unique_ptr<service_manager::Connector> connector)
+    : connector_(std::move(connector)),
+      main_thread_task_runner_(base::ThreadTaskRunnerHandle::Get()),
+      weak_ptr_factory_(this) {}
+
+BlinkConnectorImpl::~BlinkConnectorImpl() = default;
+
+void BlinkConnectorImpl::bindInterface(const char* service_name,
+                                       const char* interface_name,
+                                       mojo::ScopedMessagePipeHandle handle) {
+  // |connector_| is null in some testing contexts.
+  if (!connector_)
+    return;
+
+  if (!main_thread_task_runner_->BelongsToCurrentThread()) {
+    main_thread_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&BlinkConnectorImpl::bindInterface, GetWeakPtr(),
+                   service_name, interface_name, base::Passed(&handle)));
+    return;
+  }
+
+  // Tests might have overridden this interface with a local implementation.
+  InterfaceBinderMap* overrides_for_service =
+      GetOverridesForService(service_name);
+  if (overrides_for_service) {
+    auto it = overrides_for_service->find(std::string(interface_name));
+    if (it != overrides_for_service->end()) {
+      it->second.Run(std::move(handle));
+      return;
+    }
+  }
+
+  service_manager::Identity service_identity(
+      service_name, service_manager::mojom::kInheritUserID);
+  connector_->BindInterface(service_identity, interface_name,
+                            std::move(handle));
+}
+
+void BlinkConnectorImpl::AddOverrideForTesting(
+    const std::string& service_name,
+    const std::string& interface_name,
+    const base::Callback<void(mojo::ScopedMessagePipeHandle)>& binder) {
+  if (service_binders_.find(service_name) == service_binders_.end())
+    service_binders_[service_name] = base::MakeUnique<InterfaceBinderMap>();
+
+  (*(service_binders_[service_name]))[interface_name] = binder;
+}
+
+void BlinkConnectorImpl::ClearOverridesForTesting() {
+  service_binders_.clear();
+}
+
+base::WeakPtr<BlinkConnectorImpl> BlinkConnectorImpl::GetWeakPtr() {
+  return weak_ptr_factory_.GetWeakPtr();
+}
+
+BlinkConnectorImpl::InterfaceBinderMap*
+BlinkConnectorImpl::GetOverridesForService(const char* service_name) {
+  // Short-circuit out in the case where there are no overrides (always true in
+  // production).
+  if (service_binders_.empty())
+    return nullptr;
+
+  auto it = service_binders_.find(std::string(service_name));
+
+  if (it != service_binders_.end())
+    return it->second.get();
+
+  return nullptr;
+}
+
+}  // namespace content