Mac AVFoundation/QTKit: delay DeviceMonitorMac startup to first GetUserMedia.

content/browser/device_monitor_mac.h

Index: content/browser/device_monitor_mac.h
diff --git a/content/browser/device_monitor_mac.h b/content/browser/device_monitor_mac.h
index 6def493a81fc7a43cde27b2787828b7f42845678..696b96127b3860f885b3a497a3aef87a815ad046 100644
--- a/content/browser/device_monitor_mac.h
+++ b/content/browser/device_monitor_mac.h
@@ -7,6 +7,7 @@
 
 #include "base/basictypes.h"
 #include "base/system_monitor/system_monitor.h"
+#include "base/threading/thread_checker.h"
 
 namespace {
 class DeviceMonitorMacImpl;
@@ -22,6 +23,11 @@ class DeviceMonitorMac {
   DeviceMonitorMac();
   ~DeviceMonitorMac();
 
+  // Registers the observers for the audio/video device removal, connection and
+  // suspension. The AVFoundation library is also loaded and initialised if the
+  // OS supports it.
+  void StartMonitoring();
+
   // Method called by the internal DeviceMonitorMacImpl object
   // |device_monitor_impl_| when a device of type |type| has been added to or
   // removed from the system. This code executes in the notification thread
@@ -31,6 +37,10 @@ class DeviceMonitorMac {
  private:
   scoped_ptr<DeviceMonitorMacImpl> device_monitor_impl_;
 
+  // |thread_checker_| is used to check that constructor and StartMonitoring()
+  // are called in the correct thread, that also owns the object.
+  base::ThreadChecker thread_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(DeviceMonitorMac);
 };