Public Sessions - prompt the user for pageCapture requests

chrome/browser/extensions/api/page_capture/page_capture_permission_helper.cc

Index: chrome/browser/extensions/api/page_capture/page_capture_permission_helper.cc
diff --git a/chrome/browser/extensions/api/page_capture/page_capture_permission_helper.cc b/chrome/browser/extensions/api/page_capture/page_capture_permission_helper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b75ad274c12d3ff0d010131fa4287d42166c6fa9
--- /dev/null
+++ b/chrome/browser/extensions/api/page_capture/page_capture_permission_helper.cc
@@ -0,0 +1,135 @@
+// 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 "chrome/browser/extensions/api/page_capture/page_capture_permission_helper.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/memory/ptr_util.h"
+#include "chrome/common/pref_names.h"
+#include "chromeos/login/login_state.h"
+#include "components/prefs/pref_change_registrar.h"
+#include "components/prefs/scoped_user_pref_update.h"
+#include "extensions/common/extension.h"
+#include "extensions/common/permissions/api_permission.h"
+#include "extensions/common/permissions/api_permission_set.h"
+#include "extensions/common/permissions/manifest_permission_set.h"
+#include "extensions/common/permissions/permission_set.h"
+#include "extensions/common/url_pattern_set.h"
+
+namespace {
+
+const char kNoAvailableBrowser[] =
+    "No available browser window to show the prompt.";
+const char kUserDenied[] = "User denied request.";
+
+}  // namespace
+
+namespace extensions {
+
+PageCapturePermissionHelper::PageCapturePermissionHelper(
+    const Extension* extension,
+    PrefService* prefs,
+    const base::Closure& success_callback,
+    const base::Callback<void(const std::string&)>& failure_callback)
+    : extension_(extension),
+      prefs_(prefs),
+      success_callback_(success_callback),
+      failure_callback_(failure_callback) {}
+
+PageCapturePermissionHelper::~PageCapturePermissionHelper() {}
+
+void PageCapturePermissionHelper::HandlePermissionRequest(
+    content::WebContents* web_contents) {
+  switch (GetUserChoice()) {
+    case PermissionState::ALLOWED:
+    case PermissionState::DENIED:
+      ResolvePermissionRequest();
+      return;
+    case PermissionState::NOT_PROMPTED:
+      ShowPermissionPrompt(web_contents);
+    case PermissionState::SHOWN_PROMPT:
+      break;
+  }
+  // It's possible that several PageCapture requests come before user resolves
+  // the permission dialog, so setup a callback that gets called when pref
+  // changes (dialog is resolved).
+  pref_change_registrar_ = base::MakeUnique<PrefChangeRegistrar>();
+  pref_change_registrar_->Init(prefs_);
+  // base::Unretained is safe here because PrefChangeRegistrar will unregister
+  // callback on destruction of this object.
+  pref_change_registrar_->Add(
+      prefs::kExtensionsPublicSessionPermissions,
+      base::Bind(&PageCapturePermissionHelper::ResolvePermissionRequest,
+                 base::Unretained(this)));
+}
+
+void PageCapturePermissionHelper::ShowPermissionPrompt(
+    content::WebContents* web_contents) {
+  if (!web_contents) {
+    failure_callback_.Run(kNoAvailableBrowser);
+    return;
+  }
+  APIPermissionSet new_apis;
+  new_apis.insert(APIPermission::kPageCapture);
+  auto permission_set = base::MakeUnique<PermissionSet>(
+      new_apis, ManifestPermissionSet(), URLPatternSet(), URLPatternSet());
+
+  prompt_ = base::MakeUnique<ExtensionInstallPrompt>(web_contents);
+  prompt_->ShowDialog(
+      base::Bind(&PageCapturePermissionHelper::ResolvePermissionPrompt,
+                 base::Unretained(this)),
+      extension_,
+      nullptr,  // Uses the extension icon.
+      base::MakeUnique<ExtensionInstallPrompt::Prompt>(
+          ExtensionInstallPrompt::PERMISSIONS_PROMPT),
+      std::move(permission_set),
+      ExtensionInstallPrompt::GetDefaultShowDialogCallback());
+
+  SetUserChoice(PermissionState::SHOWN_PROMPT);
+}
+
+void PageCapturePermissionHelper::ResolvePermissionPrompt(
+    ExtensionInstallPrompt::Result prompt_result) {
+  // Dispose of the prompt as it's not needed anymore.
+  prompt_.reset();
+
+  bool allowed = prompt_result == ExtensionInstallPrompt::Result::ACCEPTED;
+  SetUserChoice(allowed ? PermissionState::ALLOWED : PermissionState::DENIED);
+}
+
+void PageCapturePermissionHelper::ResolvePermissionRequest() {
+  switch (GetUserChoice()) {
+    case PermissionState::SHOWN_PROMPT:
+      // Permission was resolved for some other extension, continue waiting.
+      return;
+    case PermissionState::DENIED:
+      failure_callback_.Run(kUserDenied);
+      break;
+    case PermissionState::ALLOWED:
+      success_callback_.Run();
+      break;
+    case PermissionState::NOT_PROMPTED:
+      NOTREACHED();
+  }
+}
+
+void PageCapturePermissionHelper::SetUserChoice(PermissionState value) {
+  DictionaryPrefUpdate update(prefs_,
+                              prefs::kExtensionsPublicSessionPermissions);
+  update->SetInteger(extension_->id(), value);
+}
+
+PageCapturePermissionHelper::PermissionState
+PageCapturePermissionHelper::GetUserChoice() {
+  const base::DictionaryValue* dictionary =
+      prefs_->GetDictionary(prefs::kExtensionsPublicSessionPermissions);
+  int value = PermissionState::NOT_PROMPTED;
+  // In case no value was set previously, we return the default value
+  // (PermissionState::NOT_PROMPTED).
+  dictionary->GetInteger(extension_->id(), &value);
+  return static_cast<PermissionState>(value);
+}
+
+}  // namespace extensions