Initialize AVFoundation explicitly

media/base/mac/avfoundation_glue.mm

 // Copyright 2013 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.
 
 #import "media/base/mac/avfoundation_glue.h"
 
 #include <dlfcn.h>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 101 matching lines @@
   NSString* AVCaptureSessionDidStopRunningNotification_;
   NSString* AVCaptureSessionErrorKey_;
   NSString* AVVideoScalingModeKey_;
   NSString* AVVideoScalingModeResizeAspectFill_;
 
   DISALLOW_COPY_AND_ASSIGN(AVFoundationInternal);
 };
 
 // This contains the logic of checking whether AVFoundation is supported.
 // It's called only once and the results are cached in a static bool.
-bool IsAVFoundationSupportedHelper() {
+bool LoadAVFoundationInternal() {
   // AVFoundation is only available on OS Lion and above.
   if (!base::mac::IsOSLionOrLater()) {
     LogCaptureApi(CAPTURE_API_QTKIT_DUE_TO_OS_PREVIOUS_TO_LION);
     return false;
   }
 
   const base::CommandLine* command_line =
       base::CommandLine::ForCurrentProcess();
   // The force-qtkit flag takes precedence over enable-avfoundation.
   if (command_line->HasSwitch(switches::kForceQTKit)) {
     LogCaptureApi(CAPTURE_API_QTKIT_FORCED_BY_FLAG);
     return false;
   }
 
   if (!command_line->HasSwitch(switches::kEnableAVFoundation)) {
     LogCaptureApi(CAPTURE_API_QTKIT_DUE_TO_NO_FLAG);
     return false;
   }
   const bool ret = [AVFoundationGlue::AVFoundationBundle() load];
   LogCaptureApi(ret ? CAPTURE_API_AVFOUNDATION_LOADED_OK
                     : CAPTURE_API_QTKIT_DUE_TO_AVFOUNDATION_LOAD_ERROR);
   return ret;
 }
 
 }  // namespace
 
 static base::LazyInstance<AVFoundationInternal>::Leaky g_avfoundation_handle =
     LAZY_INSTANCE_INITIALIZER;
 
+enum {
+  INITIALIZE_NOT_CALLED = 0,
+  AVFOUNDATION_IS_SUPPORTED,
+  AVFOUNDATION_NOT_SUPPORTED
+} static g_avfoundation_initialization = INITIALIZE_NOT_CALLED;
+
+void AVFoundationGlue::InitializeAVFoundation() {
+  CHECK([NSThread isMainThread]);
+  if (g_avfoundation_initialization != INITIALIZE_NOT_CALLED)
+    return;
+  g_avfoundation_initialization = LoadAVFoundationInternal() ?
+      AVFOUNDATION_IS_SUPPORTED : AVFOUNDATION_NOT_SUPPORTED;
+}
+
 bool AVFoundationGlue::IsAVFoundationSupported() {
-  // DeviceMonitorMac will initialize this static bool from the main UI thread
-  // once, during Chrome startup so this construction is thread safe.
-  static const bool is_supported = IsAVFoundationSupportedHelper();
-  return is_supported;
+  CHECK_NE(g_avfoundation_initialization, INITIALIZE_NOT_CALLED);
+  return g_avfoundation_initialization == AVFOUNDATION_IS_SUPPORTED;
 }
 
 NSBundle const* AVFoundationGlue::AVFoundationBundle() {
   return g_avfoundation_handle.Get().bundle();
 }
 
 NSString* AVFoundationGlue::AVCaptureDeviceWasConnectedNotification() {
   return g_avfoundation_handle.Get().AVCaptureDeviceWasConnectedNotification();
 }
 
@@ skipping 66 matching lines @@
 @implementation AVCaptureDeviceInputGlue
 
 + (CrAVCaptureDeviceInput*)deviceInputWithDevice:(CrAVCaptureDevice*)device
                                            error:(NSError**)outError {
   return [[AVFoundationGlue::AVFoundationBundle()
       classNamed:@"AVCaptureDeviceInput"] deviceInputWithDevice:device
                                                           error:outError];
 }
 
 @end  // @implementation AVCaptureDeviceInputGlue