Refactor: Make MediaCaptureDevicesDispatcher have pluggable handlers.

chrome/browser/media/extension_media_access_handler.cc

+// Copyright 2015 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/media/extension_media_access_handler.h"
+
+#include "chrome/browser/media/media_capture_devices_dispatcher.h"
+#include "chrome/browser/media/media_stream_capture_indicator.h"
+#include "chrome/browser/media/media_stream_device_permissions.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/common/pref_names.h"
+#include "content/public/browser/web_contents.h"
+#include "extensions/common/extension.h"
+#include "extensions/common/permissions/permissions_data.h"
+
+ExtensionMediaAccessHandler::ExtensionMediaAccessHandler() {
+}
+
+ExtensionMediaAccessHandler::~ExtensionMediaAccessHandler() {
+}
+
+bool ExtensionMediaAccessHandler::SupportsRequest(
+    const content::MediaStreamRequest& request,
+    const extensions::Extension* extension) {
+  return extension && (extension->is_platform_app() ||
+                       extension->is_media_request_white_listed());
+}
+
+void ExtensionMediaAccessHandler::HandleRequest(
+    content::WebContents* web_contents,
+    const content::MediaStreamRequest& request,
+    const content::MediaResponseCallback& callback,
+    const extensions::Extension* extension) {
+  // TODO(vrk): This code is largely duplicated in
+  // MediaStreamDevicesController::Accept(). Move this code into a shared method
+  // between the two classes.
+
+  Profile* profile =
+      Profile::FromBrowserContext(web_contents->GetBrowserContext());
+
+  bool audio_allowed =
+      request.audio_type == content::MEDIA_DEVICE_AUDIO_CAPTURE &&
+      extension->permissions_data()->HasAPIPermission(
+          extensions::APIPermission::kAudioCapture) &&
+      GetDevicePolicy(profile, extension->url(), prefs::kAudioCaptureAllowed,
+                      prefs::kAudioCaptureAllowedUrls) != ALWAYS_DENY;
+  bool video_allowed =
+      request.video_type == content::MEDIA_DEVICE_VIDEO_CAPTURE &&
+      extension->permissions_data()->HasAPIPermission(
+          extensions::APIPermission::kVideoCapture) &&
+      GetDevicePolicy(profile, extension->url(), prefs::kVideoCaptureAllowed,
+                      prefs::kVideoCaptureAllowedUrls) != ALWAYS_DENY;
+
+  bool get_default_audio_device = audio_allowed;
+  bool get_default_video_device = video_allowed;
+
+  content::MediaStreamDevices devices;
+
+  // Set an initial error result. If neither audio or video is allowed, we'll
+  // never try to get any device below but will just create |ui| and return an
+  // empty list with "invalid state" result. If at least one is allowed, we'll
+  // try to get device(s), and if failure, we want to return "no hardware"
+  // result.
+  // TODO(grunell): The invalid state result should be changed to a new denied
+  // result + a dcheck to ensure at least one of audio or video types is
+  // capture.
+  content::MediaStreamRequestResult result =
+      (audio_allowed || video_allowed) ? content::MEDIA_DEVICE_NO_HARDWARE
+                                       : content::MEDIA_DEVICE_INVALID_STATE;
+
+  // Get the exact audio or video device if an id is specified.
+  // We only set any error result here and before running the callback change
+  // it to OK if we have any device.
+  if (audio_allowed && !request.requested_audio_device_id.empty()) {
+    const content::MediaStreamDevice* audio_device =
+        MediaCaptureDevicesDispatcher::GetInstance()->GetRequestedAudioDevice(
+            request.requested_audio_device_id);
+    if (audio_device) {
+      devices.push_back(*audio_device);
+      get_default_audio_device = false;
+    }
+  }
+  if (video_allowed && !request.requested_video_device_id.empty()) {
+    const content::MediaStreamDevice* video_device =
+        MediaCaptureDevicesDispatcher::GetInstance()->GetRequestedVideoDevice(
+            request.requested_video_device_id);
+    if (video_device) {
+      devices.push_back(*video_device);
+      get_default_video_device = false;
+    }
+  }
+
+  // If either or both audio and video devices were requested but not
+  // specified by id, get the default devices.
+  if (get_default_audio_device || get_default_video_device) {
+    MediaCaptureDevicesDispatcher::GetInstance()->GetDefaultDevicesForProfile(
+        profile, get_default_audio_device, get_default_video_device, &devices);
+  }
+
+  scoped_ptr<content::MediaStreamUI> ui;
+  if (!devices.empty()) {
+    result = content::MEDIA_DEVICE_OK;
+    ui = MediaCaptureDevicesDispatcher::GetInstance()
+             ->GetMediaStreamCaptureIndicator()
+             ->RegisterMediaStream(web_contents, devices);
+  }
+
+  callback.Run(devices, result, ui.Pass());
+}