Wrote audio- and video-only WebRTC call tests.

chrome/browser/automation/testing_automation_provider.cc

Index: chrome/browser/automation/testing_automation_provider.cc
diff --git a/chrome/browser/automation/testing_automation_provider.cc b/chrome/browser/automation/testing_automation_provider.cc
index 47036a383d9ad8c1c5622eaaae314a1f84401187..8c04533a26fe6ddf86c7b9b32fd803b4265d2b3d 100644
--- a/chrome/browser/automation/testing_automation_provider.cc
+++ b/chrome/browser/automation/testing_automation_provider.cc
@@ -2258,8 +2258,15 @@ void TestingAutomationProvider::PerformActionOnInfobar(
           media_stream_infobar->GetVideoDevices();
       content::MediaStreamDevices audio_devices =
           media_stream_infobar->GetAudioDevices();
-      if (video_devices.empty() || audio_devices.empty()) {
-        reply.SendError("No available audio/video devices to autoselect.");
+

[phoglund_chromium, 2012/11/29 10:11:36]

HasVideo() == true -> web page actually requested video.

+      if (media_stream_infobar->HasVideo() && video_devices.empty()) {
+        reply.SendError("Requested video, but there are no video "
+                        "devices on the system.");
+        return;
+      }
+      if (media_stream_infobar->HasAudio() && audio_devices.empty()) {
+        reply.SendError("Requested audio, but there are no audio "
+            "devices on the system.");
         return;
       }