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// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_RENDERER_HOST_PROCESS_SELECTION_DEFERRING_CONDITION_RUNNER_H_
#define CONTENT_BROWSER_RENDERER_HOST_PROCESS_SELECTION_DEFERRING_CONDITION_RUNNER_H_
#include <memory>
#include <vector>
#include "base/functional/callback.h"
#include "base/memory/raw_ref.h"
#include "base/memory/weak_ptr.h"
#include "content/common/content_export.h"
namespace content {
class NavigationRequest;
class ProcessSelectionDeferringCondition;
// Helper class to defer renderer process selection until dependencies are
// ready.
//
// Clients subclass the `ProcessSelectionDeferringCondition` class in order to
// initiate asynchronous tasks at navigation start, update the tasks on
// redirects, and be given the opportunity to defer the selection of the
// renderer process until the condition's tasks have completed. The client
// should register their subclass in
// `RegisterProcessSelectionDeferringConditions`, or in the embedder's
// `ContentBrowserClient::CreateProcessSelectionDeferringConditionsForNavigation()`
// method.
//
// The mechanism is not applied for prerender activations or about:blank or
// same-document navigations.
//
// TODO(crbug.com/439013866): add support for tracing.
class CONTENT_EXPORT ProcessSelectionDeferringConditionRunner {
public:
// Creates the runner, asks the embedder for any conditions that it wishes to
// register, and then starts the conditions.
static std::unique_ptr<ProcessSelectionDeferringConditionRunner> Create(
NavigationRequest& navigation_request);
ProcessSelectionDeferringConditionRunner(
const ProcessSelectionDeferringConditionRunner&) = delete;
ProcessSelectionDeferringConditionRunner& operator=(
const ProcessSelectionDeferringConditionRunner&) = delete;
~ProcessSelectionDeferringConditionRunner();
// Called by NavigationRequest::OnRequestRedirected(). This calls
// OnRequestRedirected() on each of the conditions that have been registered.
void OnRequestRedirected();
// Called prior to process selection. This calls
// `ProcessSelectionDeferringCondition::OnWillSelectFinalProcess()` on each
// registered condition. Registered conditions are given the opportunity to
// defer the process selection.
void WillSelectFinalProcess(base::OnceClosure on_completion_callback);
private:
friend class ProcessSelectionDeferringConditionRunnerTest;
ProcessSelectionDeferringConditionRunner();
// Registers `ProcessSelectionDeferringCondition` instances that will be
// processed during the navigation.
void RegisterProcessSelectionDeferringConditions(
NavigationRequest& navigation_request);
// Processes the next condition on the list.
void ProcessNextCondition();
// Called asynchronously by `RegisterProcessSelectionDeferringConditions` to
// continue processing after deferring.
void ResumeProcessing();
std::vector<std::unique_ptr<ProcessSelectionDeferringCondition>>
deferring_conditions_;
// Called after all conditions have completed.
base::OnceClosure on_completion_callback_;
base::WeakPtrFactory<ProcessSelectionDeferringConditionRunner> weak_factory_{
this};
};
} // namespace content
#endif // CONTENT_BROWSER_RENDERER_HOST_PROCESS_SELECTION_DEFERRING_CONDITION_RUNNER_H_
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