Add VTSupport for dynamically linking VideoToolbox.

content/common/gpu/media/vt_support.cc

+// Copyright 2014 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.
+
+#include <dlfcn.h>
+
+#include "base/memory/singleton.h"
+#include "content/common/gpu/media/vt_support.h"
+
+namespace content {
+
+// static
+VTSupport* VTSupport::GetInstance() {
+  VTSupport* vt_support = Singleton<VTSupport>::get();
+  if (vt_support->Initialized())
+    return vt_support;
+  return NULL;
+}
+
+VTSupport::VTSupport()
+    : cm_handle_(NULL),
+      initialized_(false) {
+  cm_handle_ = dlopen(
+      "/System/Library/Frameworks/CoreMedia.framework/CoreMedia",
+      RTLD_LAZY | RTLD_LOCAL);
+  // TODO(sandersd): Attempt fallback to private framework.
+  vt_handle_ = dlopen(
+      "/System/Library/Frameworks/VideoToolbox.framework/VideoToolbox",
+      RTLD_LAZY | RTLD_LOCAL);

[mcasas, 2014/06/19 12:04:23]

First create the Bundle and then dlopen() it:

NSBundle* bundle = [NSBundle bundleWithPath:
    @"/System/Library/Frameworks/VideoToolbox.framework/VideoToolbox"];

const char* path = [[bundle executablePath] fileSystemRepresentation];
CHECK(path);
void* library_handle = dlopen(path, RTLD_LAZY | RTLD_LOCAL);
(D)CHECK(library_handle) << dlerror();

+  if (!cm_handle_ || !vt_handle_)
+    return;
+
+  CMBlockBufferCreateWithMemoryBlock =
+      reinterpret_cast<CMBlockBufferCreateWithMemoryBlockPtr>(
+        dlsym(cm_handle_, "CMBlockBufferCreateWithMemoryBlock"));

[mcasas, 2014/06/19 12:04:24]

CHECK(CMBlockBufferCreateWithMemoryBlock) << dlerror(); ?

+  CMFormatDescriptionGetExtensions =
+      reinterpret_cast<CMFormatDescriptionGetExtensionsPtr>(
+          dlsym(cm_handle_, "CMFormatDescriptionGetExtensions"));
+  CMSampleBufferCreate =
+      reinterpret_cast<CMSampleBufferCreatePtr>(
+          dlsym(cm_handle_, "CMSampleBufferCreate"));
+  // TODO(sandersd): Make CreateFromH264 optional.
+  CMVideoFormatDescriptionCreateFromH264ParameterSets =
+      reinterpret_cast<CMVideoFormatDescriptionCreateFromH264ParameterSetsPtr>(
+          dlsym(cm_handle_,
+              "CMVideoFormatDescriptionCreateFromH264ParameterSets"));
+
+  VTDecompressionSessionDecodeFrame =
+      reinterpret_cast<VTDecompressionSessionDecodeFramePtr>(
+          dlsym(vt_handle_, "VTDecompressionSessionDecodeFrame"));
+  VTDecompressionSessionCreate =
+      reinterpret_cast<VTDecompressionSessionCreatePtr>(
+          dlsym(vt_handle_, "VTDecompressionSessionCreate"));
+
+  if (!CMBlockBufferCreateWithMemoryBlock ||
+      !CMFormatDescriptionGetExtensions ||
+      !CMSampleBufferCreate ||
+      !CMVideoFormatDescriptionCreateFromH264ParameterSets ||
+      !VTDecompressionSessionDecodeFrame ||
+      !VTDecompressionSessionCreate) {
+    CloseLibraryHandles();
+    return;
+  }
+
+  initialized_ = true;
+}
+
+VTSupport::~VTSupport() {
+  CloseLibraryHandles();
+}
+
+bool VTSupport::Initialized() {
+  return initialized_;
+}
+
+void VTSupport::CloseLibraryHandles() {
+  if (cm_handle_) {
+    dlclose(cm_handle_);
+    cm_handle_ = NULL;
+  }
+  if (vt_handle_) {
+    dlclose(vt_handle_);
+    vt_handle_ = NULL;
+  }
+}
+
+}  // namespace content