Public Sessions - prompt the user for tabCapture requests

chrome/browser/media/webrtc/public_session_tab_capture_access_handler.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 CHROME_BROWSER_MEDIA_WEBRTC_PUBLIC_SESSION_TAB_CAPTURE_ACCESS_HANDLER_H_
+#define CHROME_BROWSER_MEDIA_WEBRTC_PUBLIC_SESSION_TAB_CAPTURE_ACCESS_HANDLER_H_
+
+#include "base/macros.h"
+#include "chrome/browser/extensions/extension_install_prompt.h"
+#include "chrome/browser/media/capture_access_handler_base.h"
+#include "chrome/browser/media/webrtc/tab_capture_access_handler.h"
+#include "content/public/common/media_stream_request.h"
+#include "extensions/common/extension_id.h"
+
+// MediaAccessHandler for TabCapture API in Public Sessions. This class is
+// implemented as a wrapper around TabCaptureAccessHandler. It allows for finer
+// access control to TabCapture manifest permission feature inside of Public
+// Sessions.
+//
+// In Public Sessions, extensions (and apps) are force-installed by admin policy
+// so the user does not get a chance to review the permissions for these
+// extensions. This is not acceptable from a security/privacy standpoint, so
+// when an extension uses the TabCapture API for the first time, we show the
+// user a dialog where they can choose whether to allow the extension access to
+// the API.
+class PublicSessionTabCaptureAccessHandler : public CaptureAccessHandlerBase {
+ public:
+  PublicSessionTabCaptureAccessHandler();
+  ~PublicSessionTabCaptureAccessHandler() override;
+
+  // MediaAccessHandler implementation.
+  bool SupportsStreamType(const content::MediaStreamType type,
+                          const extensions::Extension* extension) override;
+  bool CheckMediaAccessPermission(
+      content::WebContents* web_contents,
+      const GURL& security_origin,
+      content::MediaStreamType type,
+      const extensions::Extension* extension) override;
+  void HandleRequest(content::WebContents* web_contents,
+                     const content::MediaStreamRequest& request,
+                     const content::MediaResponseCallback& callback,
+                     const extensions::Extension* extension) override;
+
+ private:
+  // Helper function used to chain the HandleRequest call into the original
+  // inside of TabCaptureAccessHandler.
+  void ChainHandleRequest(content::WebContents* web_contents,
+                          const content::MediaStreamRequest& request,
+                          const content::MediaResponseCallback& callback,
+                          const extensions::Extension* extension);
+
+  // Function used to resolve user decision regarding allowing tab capture.
+  void ResolvePermissionPrompt(
+      content::WebContents* web_contents,
+      const content::MediaStreamRequest& request,
+      const content::MediaResponseCallback& callback,
+      const extensions::Extension* extension,
+      ExtensionInstallPrompt::Result prompt_result);
+
+  // Class used to cache user choice regarding allowing tab capture.
+  class UserChoice {
+   public:
+    // Helper function for checking if tab capture is allowed by user choice.
+    bool IsAllowed() const;
+    // Helper function which returns true if user choice wasn't prompted yet.
+    bool NeedsPrompting() const;
+    void Set(bool allowed);
+    void SetPrompted();
+
+   private:
+    bool tab_capture_prompted_ = false;
+    bool tab_capture_allowed_ = false;
+  };
+
+  std::map<extensions::ExtensionId, UserChoice> user_choice_cache_;
+  std::map<extensions::ExtensionId, std::unique_ptr<ExtensionInstallPrompt>>
+      extension_install_prompt_map_;
+  TabCaptureAccessHandler tab_capture_access_handler_;
+
+  DISALLOW_COPY_AND_ASSIGN(PublicSessionTabCaptureAccessHandler);
+};
+
+#endif  // CHROME_BROWSER_MEDIA_WEBRTC_PUBLIC_SESSION_TAB_CAPTURE_ACCESS_HANDLER_H_