Allow AllocateGpuMemoryBuffer to be called from multiple threads.

ui/gl/io_surface_support_mac.cc

Index: ui/gl/io_surface_support_mac.cc
diff --git a/ui/gl/io_surface_support_mac.cc b/ui/gl/io_surface_support_mac.cc
index a7aeae85f8e5ca828aed8e15520041787dd09ff3..34b922d3840f1d3bbd4688cac14ffb73d5386894 100644
--- a/ui/gl/io_surface_support_mac.cc
+++ b/ui/gl/io_surface_support_mac.cc
@@ -22,6 +22,9 @@ typedef IOReturn (*IOSurfaceLockPtr)(CFTypeRef io_surface,
 typedef IOReturn (*IOSurfaceUnlockPtr)(CFTypeRef io_surface,
                                        uint32 options,
                                        uint32* seed);
+typedef void (*IOSurfaceDecrementUseCountPtr)(CFTypeRef io_surface);
+typedef void (*IOSurfaceIncrementUseCountPtr)(CFTypeRef io_surface);
+typedef Boolean (*IOSurfaceIsInUsePtr)(CFTypeRef io_surface);
 
 typedef CGLError (*CGLTexImageIOSurface2DProcPtr)(CGLContextObj ctx,
                                                   GLenum target,
@@ -67,6 +70,10 @@ class IOSurfaceSupportImpl : public IOSurfaceSupport {
                                    uint32 options,
                                    uint32* seed) OVERRIDE;
 
+  virtual void IOSurfaceDecrementUseCount(CFTypeRef io_surface) OVERRIDE;
+  virtual void IOSurfaceIncrementUseCount(CFTypeRef io_surface) OVERRIDE;
+  virtual Boolean IOSurfaceIsInUse(CFTypeRef io_surface) OVERRIDE;
+
   virtual CGLError CGLTexImageIOSurface2D(CGLContextObj ctx,
                                           GLenum target,
                                           GLenum internal_format,
@@ -105,6 +112,10 @@ class IOSurfaceSupportImpl : public IOSurfaceSupport {
   IOSurfaceGetBaseAddressPtr io_surface_get_base_address_;
   IOSurfaceLockPtr io_surface_lock_;
   IOSurfaceUnlockPtr io_surface_unlock_;
+  IOSurfaceDecrementUseCountPtr io_surface_decrement_use_count_;
+  IOSurfaceIncrementUseCountPtr io_surface_increment_use_count_;
+  IOSurfaceIsInUsePtr io_surface_is_in_use_;
+
   CGLTexImageIOSurface2DProcPtr cgl_tex_image_io_surface_2d_;
   CVPixelBufferGetIOSurfaceProcPtr cv_pixel_buffer_get_io_surface_;
   bool initialized_successfully_;
@@ -190,6 +201,19 @@ IOReturn IOSurfaceSupportImpl::IOSurfaceUnlock(CFTypeRef io_surface,
   return io_surface_unlock_(io_surface, options, seed);
 }
 
+void IOSurfaceSupportImpl::IOSurfaceDecrementUseCount(CFTypeRef io_surface) {
+  io_surface_decrement_use_count_(io_surface);
+}
+
+void IOSurfaceSupportImpl::IOSurfaceIncrementUseCount(CFTypeRef io_surface) {
+  io_surface_increment_use_count_(io_surface);
+}
+
+Boolean IOSurfaceSupportImpl::IOSurfaceIsInUse(CFTypeRef io_surface) {
+  return io_surface_is_in_use_(io_surface);
+}
+
+
 CGLError IOSurfaceSupportImpl::CGLTexImageIOSurface2D(CGLContextObj ctx,
                                                       GLenum target,
                                                       GLenum internal_format,
@@ -235,6 +259,9 @@ IOSurfaceSupportImpl::IOSurfaceSupportImpl()
       io_surface_get_base_address_(NULL),
       io_surface_lock_(NULL),
       io_surface_unlock_(NULL),
+      io_surface_decrement_use_count_(NULL),
+      io_surface_increment_use_count_(NULL),
+      io_surface_is_in_use_(NULL),
       cgl_tex_image_io_surface_2d_(NULL),
       cv_pixel_buffer_get_io_surface_(NULL),
       initialized_successfully_(false) {
@@ -279,6 +306,13 @@ IOSurfaceSupportImpl::IOSurfaceSupportImpl()
       dlsym(iosurface_handle_, "IOSurfaceGetBaseAddress");
   void* io_surface_lock_ptr = dlsym(iosurface_handle_, "IOSurfaceLock");
   void* io_surface_unlock_ptr = dlsym(iosurface_handle_, "IOSurfaceUnlock");
+  void* io_surface_decrement_use_count_ptr =
+      dlsym(iosurface_handle_, "IOSurfaceDecrementUseCount");
+  void* io_surface_increment_use_count_ptr =
+      dlsym(iosurface_handle_, "IOSurfaceIncrementUseCount");
+  void* io_surface_is_in_use_ptr =
+      dlsym(iosurface_handle_, "IOSurfaceIsInUse");
+
   void* tex_image_io_surface_2d_ptr =
       dlsym(opengl_handle_, "CGLTexImageIOSurface2D");
   void* cv_pixel_buffer_get_io_surface =
@@ -299,6 +333,9 @@ IOSurfaceSupportImpl::IOSurfaceSupportImpl()
       !io_surface_get_base_address_ptr ||
       !io_surface_lock_ptr ||
       !io_surface_unlock_ptr ||
+      !io_surface_decrement_use_count_ptr ||
+      !io_surface_increment_use_count_ptr ||
+      !io_surface_is_in_use_ptr ||
       !tex_image_io_surface_2d_ptr ||
       !cv_pixel_buffer_get_io_surface) {
     CloseLibraryHandles();
@@ -339,6 +376,14 @@ IOSurfaceSupportImpl::IOSurfaceSupportImpl()
   io_surface_lock_ = reinterpret_cast<IOSurfaceLockPtr>(io_surface_lock_ptr);
   io_surface_unlock_ = reinterpret_cast<IOSurfaceUnlockPtr>(
       io_surface_unlock_ptr);
+  io_surface_decrement_use_count_ =
+      reinterpret_cast<IOSurfaceDecrementUseCountPtr>(
+          io_surface_decrement_use_count_ptr);
+  io_surface_increment_use_count_ =
+      reinterpret_cast<IOSurfaceIncrementUseCountPtr>(
+          io_surface_increment_use_count_ptr);
+  io_surface_is_in_use_ =
+      reinterpret_cast<IOSurfaceIsInUsePtr>(io_surface_is_in_use_ptr);
   cgl_tex_image_io_surface_2d_ =
       reinterpret_cast<CGLTexImageIOSurface2DProcPtr>(
           tex_image_io_surface_2d_ptr);