Add CHECK to EnumerateDevices call in PepperDeviceManager

BUG=666715

Review-Url: https://codereview.chromium.org/2516603003
Cr-Commit-Position: refs/heads/master@{#433417}
(cherry picked from commit 48c91fb)

Review URL: https://codereview.chromium.org/2519273003 .

Cr-Commit-Position: refs/branch-heads/2924@{#55}
Cr-Branched-From: 3a87aec-refs/heads/master@{#433059}

Author: Guido Urdaneta

content/renderer/pepper/pepper_media_device_manager.cc

@@ -81,6 +81,7 @@ void PepperMediaDeviceManager::EnumerateDevices(
 #if defined(ENABLE_WEBRTC)
   bool request_audio_input = type == PP_DEVICETYPE_DEV_AUDIOCAPTURE;
   bool request_video_input = type == PP_DEVICETYPE_DEV_VIDEOCAPTURE;
+  CHECK(request_audio_input || request_video_input);
   GetMediaDevicesDispatcher()->EnumerateDevices(
       request_audio_input, request_video_input, false /* audio_output */,
       url::Origin(document_url.GetOrigin()),