[fuchsia] Implement NavigationPolicyThrottle for navigation blocking

* Add an implementation of NavigationPolicyThrottle to WebEngine
* Add NavigationPolicyHandler, which keeps track of throttles and checks
  if navigations need to be passed on to the client
* Add a FakeNavigationPolicyProvider for tests

Test: NavigationPolicyThrottleTest
Bug: 1117601
Change-Id: I0bdf94345b10d829bea4aeb85f74204970a97239
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2519039
Commit-Queue: Sharon Yang <[email protected]>
Reviewed-by: Sergey Ulanov <[email protected]>
Cr-Commit-Position: refs/heads/master@{#826625}

fuchsia/engine/BUILD.gn

@@ -157,6 +157,10 @@ component("web_engine_core") {
     "browser/media_resource_provider_service.h",
     "browser/navigation_controller_impl.cc",
     "browser/navigation_controller_impl.h",
+    "browser/navigation_policy_handler.cc",
+    "browser/navigation_policy_handler.h",
+    "browser/navigation_policy_throttle.cc",
+    "browser/navigation_policy_throttle.h",
     "browser/url_request_rewrite_rules_manager.cc",
     "browser/url_request_rewrite_rules_manager.h",
     "browser/web_engine_browser_context.cc",
@@ -329,8 +333,11 @@ test("web_engine_unittests") {
     "browser/ax_tree_converter_unittest.cc",
     "browser/cookie_manager_impl_unittest.cc",
     "browser/event_filter_unittest.cc",
+    "browser/fake_navigation_policy_provider.cc",
+    "browser/fake_navigation_policy_provider.h",
     "browser/frame_impl_unittest.cc",
     "browser/media_player_impl_unittest.cc",
+    "browser/navigation_policy_throttle_unittest.cc",
     "browser/url_request_rewrite_rules_manager_unittest.cc",
     "common/web_engine_url_loader_throttle_unittest.cc",
     "context_provider_impl_unittest.cc",
@@ -343,6 +350,7 @@ test("web_engine_unittests") {
     ":switches",
     ":web_engine_core",
     "//base/test:test_support",
+    "//content/test:test_support",
     "//fuchsia/base:test_support",
     "//mojo/core/embedder",
     "//services/media_session/public/mojom",

fuchsia/engine/browser/fake_navigation_policy_provider.cc

@@ -0,0 +1,30 @@
+// Copyright 2020 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 "fuchsia/engine/browser/fake_navigation_policy_provider.h"
+
+#include "base/logging.h"
+#include "base/notreached.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+FakeNavigationPolicyProvider::FakeNavigationPolicyProvider() = default;
+
+FakeNavigationPolicyProvider::~FakeNavigationPolicyProvider() = default;
+
+void FakeNavigationPolicyProvider::EvaluateRequestedNavigation(
+    fuchsia::web::RequestedNavigation requested_navigation,
+    EvaluateRequestedNavigationCallback callback) {
+  fuchsia::web::NavigationDecision decision;
+  if (should_reject_request_) {
+    callback(decision.WithAbort(fuchsia::web::NoArgumentsAction()));
+  } else {
+    callback(decision.WithProceed(fuchsia::web::NoArgumentsAction()));
+  }
+
+  requested_navigation_ = std::move(requested_navigation);
+}
+
+void FakeNavigationPolicyProvider::NotImplemented_(const std::string& name) {
+  NOTIMPLEMENTED() << name;
+}

fuchsia/engine/browser/fake_navigation_policy_provider.h

@@ -0,0 +1,40 @@
+// Copyright 2020 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 FUCHSIA_ENGINE_BROWSER_FAKE_NAVIGATION_POLICY_PROVIDER_H_
+#define FUCHSIA_ENGINE_BROWSER_FAKE_NAVIGATION_POLICY_PROVIDER_H_
+
+#include <fuchsia/web/cpp/fidl.h>
+#include <fuchsia/web/cpp/fidl_test_base.h>
+
+class FakeNavigationPolicyProvider
+    : public fuchsia::web::testing::NavigationPolicyProvider_TestBase {
+ public:
+  FakeNavigationPolicyProvider();
+  ~FakeNavigationPolicyProvider() override;
+
+  FakeNavigationPolicyProvider(const FakeNavigationPolicyProvider&) = delete;
+  FakeNavigationPolicyProvider& operator=(const FakeNavigationPolicyProvider&) =
+      delete;
+
+  void set_should_reject_request(bool reject) {
+    should_reject_request_ = reject;
+  }
+
+  fuchsia::web::RequestedNavigation* requested_navigation() {
+    return &requested_navigation_;
+  }
+
+  // fuchsia::web::NavigationPolicyProvider implementation.
+  void EvaluateRequestedNavigation(
+      fuchsia::web::RequestedNavigation requested_navigation,
+      EvaluateRequestedNavigationCallback callback) final;
+  void NotImplemented_(const std::string& name) final;
+
+ private:
+  fuchsia::web::RequestedNavigation requested_navigation_;
+  bool should_reject_request_ = false;
+};
+
+#endif  // FUCHSIA_ENGINE_BROWSER_FAKE_NAVIGATION_POLICY_PROVIDER_H_

fuchsia/engine/browser/navigation_policy_handler.cc

@@ -0,0 +1,69 @@
+// Copyright 2020 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 "fuchsia/engine/browser/navigation_policy_handler.h"
+
+#include <lib/fidl/cpp/binding.h>
+
+#include "base/fuchsia/fuchsia_logging.h"
+#include "content/public/browser/navigation_handle.h"
+#include "fuchsia/engine/browser/navigation_policy_throttle.h"
+
+NavigationPolicyHandler::NavigationPolicyHandler(
+    fuchsia::web::NavigationPolicyProviderParams params,
+    fidl::InterfaceHandle<fuchsia::web::NavigationPolicyProvider> delegate)
+    : params_(std::move(params)), provider_(delegate.Bind()) {
+  provider_.set_error_handler(fit::bind_member(
+      this, &NavigationPolicyHandler::OnNavigationPolicyProviderDisconnected));
+}
+
+NavigationPolicyHandler::~NavigationPolicyHandler() {
+  for (auto* throttle : navigation_throttles_) {
+    throttle->OnNavigationPolicyProviderDisconnected(
+        content::NavigationThrottle::CANCEL);
+  }
+  navigation_throttles_.clear();
+}
+
+void NavigationPolicyHandler::RegisterNavigationThrottle(
+    NavigationPolicyThrottle* navigation_throttle) {
+  navigation_throttles_.insert(navigation_throttle);
+}
+
+void NavigationPolicyHandler::RemoveNavigationThrottle(
+    NavigationPolicyThrottle* navigation_throttle) {
+  navigation_throttles_.erase(navigation_throttle);
+}
+
+void NavigationPolicyHandler::EvaluateRequestedNavigation(
+    fuchsia::web::RequestedNavigation requested_navigation,
+    fuchsia::web::NavigationPolicyProvider::EvaluateRequestedNavigationCallback
+        callback) {
+  provider_->EvaluateRequestedNavigation(std::move(requested_navigation),
+                                         std::move(callback));
+}
+
+bool NavigationPolicyHandler::ShouldEvaluateNavigation(
+    content::NavigationHandle* handle,
+    fuchsia::web::NavigationPhase phase) {
+  if (handle->IsInMainFrame()) {
+    return (phase & params_.main_frame_phases()) == phase;
+  }
+
+  return (phase & params_.subframe_phases()) == phase;
+}
+
+bool NavigationPolicyHandler::is_provider_connected() {
+  return provider_.is_bound();
+}
+
+void NavigationPolicyHandler::OnNavigationPolicyProviderDisconnected(
+    zx_status_t status) {
+  ZX_LOG(ERROR, status) << "NavigationPolicyProvider disconnected";
+  for (auto* throttle : navigation_throttles_) {
+    throttle->OnNavigationPolicyProviderDisconnected(
+        content::NavigationThrottle::CANCEL);
+  }
+  navigation_throttles_.clear();
+}

fuchsia/engine/browser/navigation_policy_handler.h

@@ -0,0 +1,59 @@
+// Copyright 2020 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 FUCHSIA_ENGINE_BROWSER_NAVIGATION_POLICY_HANDLER_H_
+#define FUCHSIA_ENGINE_BROWSER_NAVIGATION_POLICY_HANDLER_H_
+
+#include <fuchsia/web/cpp/fidl.h>
+
+#include "base/containers/flat_set.h"
+
+class NavigationPolicyThrottle;
+
+namespace content {
+class NavigationHandle;
+}  // namespace content
+
+class NavigationPolicyHandler {
+ public:
+  NavigationPolicyHandler(
+      fuchsia::web::NavigationPolicyProviderParams params,
+      fidl::InterfaceHandle<fuchsia::web::NavigationPolicyProvider> delegate);
+  ~NavigationPolicyHandler();
+
+  NavigationPolicyHandler(const NavigationPolicyHandler&) = delete;
+  NavigationPolicyHandler& operator=(const NavigationPolicyHandler&) = delete;
+
+  void RegisterNavigationThrottle(
+      NavigationPolicyThrottle* navigation_throttle);
+  void RemoveNavigationThrottle(NavigationPolicyThrottle* navigation_throttle);
+
+  fuchsia::web::NavigationPolicyProvider* navigation_policy_provider() {
+    return provider_.get();
+  }
+
+  bool is_provider_connected();
+
+  // Passes on the call to |provider_|.
+  void EvaluateRequestedNavigation(
+      fuchsia::web::RequestedNavigation requested_navigation,
+      fuchsia::web::NavigationPolicyProvider::
+          EvaluateRequestedNavigationCallback callback);
+
+  // Determines whether or not the client is interested in evaluating |handle|.
+  bool ShouldEvaluateNavigation(content::NavigationHandle* handle,
+                                fuchsia::web::NavigationPhase phase);
+
+ private:
+  void OnNavigationPolicyProviderDisconnected(zx_status_t status);
+
+  fuchsia::web::NavigationPolicyProviderParams params_;
+  fuchsia::web::NavigationPolicyProviderPtr provider_;
+
+  // Keeps track of the NavigationThrottles associated with the Frame that owns
+  // |this|.
+  base::flat_set<NavigationPolicyThrottle*> navigation_throttles_;
+};
+
+#endif  // FUCHSIA_ENGINE_BROWSER_NAVIGATION_POLICY_HANDLER_H_

fuchsia/engine/browser/navigation_policy_throttle.cc

@@ -0,0 +1,122 @@
+// Copyright 2020 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 "fuchsia/engine/browser/navigation_policy_throttle.h"
+
+#include "content/public/browser/navigation_handle.h"
+#include "fuchsia/engine/browser/navigation_policy_handler.h"
+
+namespace {
+
+fuchsia::web::RequestedNavigation ToRequestedNavigation(
+    content::NavigationHandle* handle,
+    fuchsia::web::NavigationPhase phase) {
+  fuchsia::web::RequestedNavigation event;
+  event.set_id(static_cast<uint64_t>(handle->GetNavigationId()));
+  event.set_phase(phase);
+  event.set_is_main_frame(handle->IsInMainFrame());
+  event.set_is_same_document(handle->IsSameDocument());
+  event.set_is_http_post(handle->IsPost());
+  event.set_url(handle->GetURL().spec());
+  event.set_has_gesture(handle->HasUserGesture());
+  event.set_was_server_redirect(handle->WasServerRedirect());
+
+  return event;
+}
+
+}  // namespace
+
+NavigationPolicyThrottle::NavigationPolicyThrottle(
+    content::NavigationHandle* handle,
+    NavigationPolicyHandler* policy_handler)
+    : NavigationThrottle(handle),
+      policy_handler_(policy_handler),
+      navigation_handle_(handle) {
+  if (policy_handler->is_provider_connected()) {
+    policy_handler_->RegisterNavigationThrottle(this);
+  } else {
+    policy_handler_ = nullptr;
+  }
+}
+
+NavigationPolicyThrottle::~NavigationPolicyThrottle() {
+  if (policy_handler_)
+    policy_handler_->RemoveNavigationThrottle(this);
+}
+
+void NavigationPolicyThrottle::OnNavigationPolicyProviderDisconnected(
+    content::NavigationThrottle::ThrottleCheckResult check_result) {
+  if (is_paused_) {
+    CancelDeferredNavigation(check_result);
+    is_paused_ = false;
+  }
+
+  policy_handler_ = nullptr;
+}
+
+void NavigationPolicyThrottle::OnRequestedNavigationEvaluated(
+    fuchsia::web::NavigationDecision decision) {
+  DCHECK(is_paused_);
+
+  switch (decision.Which()) {
+    case fuchsia::web::NavigationDecision::kProceed:
+      Resume();
+      break;
+    case fuchsia::web::NavigationDecision::kAbort:
+      CancelDeferredNavigation(content::NavigationThrottle::CANCEL);
+      break;
+    default:
+      NOTREACHED();
+  }
+  is_paused_ = false;
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+NavigationPolicyThrottle::WillStartRequest() {
+  return HandleNavigationPhase(fuchsia::web::NavigationPhase::START);
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+NavigationPolicyThrottle::WillRedirectRequest() {
+  return HandleNavigationPhase(fuchsia::web::NavigationPhase::REDIRECT);
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+NavigationPolicyThrottle::WillFailRequest() {
+  return HandleNavigationPhase(fuchsia::web::NavigationPhase::FAIL);
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+NavigationPolicyThrottle::WillProcessResponse() {
+  return HandleNavigationPhase(fuchsia::web::NavigationPhase::PROCESS_RESPONSE);
+}
+
+const char* NavigationPolicyThrottle::GetNameForLogging() {
+  return "NavigationPolicyThrottle";
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+NavigationPolicyThrottle::HandleNavigationPhase(
+    fuchsia::web::NavigationPhase phase) {
+  DCHECK(!is_paused_);
+
+  if (!policy_handler_) {
+    return content::NavigationThrottle::ThrottleCheckResult(
+        content::NavigationThrottle::CANCEL);
+  }
+
+  if (!policy_handler_->ShouldEvaluateNavigation(navigation_handle_, phase)) {
+    return content::NavigationThrottle::ThrottleCheckResult(
+        content::NavigationThrottle::PROCEED);
+  }
+
+  policy_handler_->navigation_policy_provider()->EvaluateRequestedNavigation(
+      ToRequestedNavigation(navigation_handle_, phase),
+      fit::bind_member(
+          this, &NavigationPolicyThrottle::OnRequestedNavigationEvaluated));
+
+  is_paused_ = true;
+  return content::NavigationThrottle::ThrottleCheckResult(
+      content::NavigationThrottle::DEFER);
+}