Adds UMA histograms for desktop tab and audio capture through

content/browser/renderer_host/media/video_capture_manager.cc

Index: content/browser/renderer_host/media/video_capture_manager.cc
diff --git a/content/browser/renderer_host/media/video_capture_manager.cc b/content/browser/renderer_host/media/video_capture_manager.cc
index 8e84fdd8441db69efeec858ea857c51bc2490173..4016235c8f8bc5d0fe09c6d4ddb9674612449837 100644
--- a/content/browser/renderer_host/media/video_capture_manager.cc
+++ b/content/browser/renderer_host/media/video_capture_manager.cc
@@ -21,6 +21,7 @@
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "build/build_config.h"
+#include "content/browser/media/capture/desktop_capture_device_uma_types.h"
 #include "content/browser/media/capture/web_contents_video_capture_device.h"
 #include "content/browser/media/media_internals.h"
 #include "content/browser/renderer_host/media/video_capture_controller.h"
@@ -524,6 +525,7 @@ VideoCaptureManager::DoStartDesktopCaptureOnDeviceThread(
 
   if (desktop_id.type == DesktopMediaID::TYPE_WEB_CONTENTS) {
     video_capture_device.reset(WebContentsVideoCaptureDevice::Create(id));
+    IncrementDesktopCaptureCounter(TAB_VIDEO_CAPTURER_CREATED);
   } else {
 #if defined(USE_AURA)
     video_capture_device = DesktopCaptureDeviceAura::Create(desktop_id);