Load VideoToolbox even when --no-sandbox is in use.

content/common/gpu/media/vt_video_decode_accelerator.cc

Index: content/common/gpu/media/vt_video_decode_accelerator.cc
diff --git a/content/common/gpu/media/vt_video_decode_accelerator.cc b/content/common/gpu/media/vt_video_decode_accelerator.cc
index d4ad116c39304c12eca8c2894220897269aa7b20..a3764e8cde8476e2f13aca0848c0aabf9c044c35 100644
--- a/content/common/gpu/media/vt_video_decode_accelerator.cc
+++ b/content/common/gpu/media/vt_video_decode_accelerator.cc
@@ -32,6 +32,11 @@ using content_common_gpu_media::StubPathMap;
 
 namespace content {
 
+// Track VideoToolbox loaded to make sure that loading is attempted once and

[DaleCurtis, 2014/12/04 01:57:31]

Seems instead you should be using a LazyInstance::Leaky to ensure startup is
only attempted once. See how this is done in media/base/media.cc --
Alternatively you can find a place which can track this without the use of
globals (note: we typically prefix these with "g_" too)

[sandersd (OOO until July 31), 2014/12/04 02:05:48]

That seems rather complicated for this use case, specifically because there is
no actual object to represent the loaded library (so a fake one would need to be
created).

The generated stub does include its own static that has this information
(accessed by IsVtInitialized() as the previous code did), but if I use that from
Initialize() then it will try to load it every time if it is failing.

I could remove g_vt_load_successful and use acombination of g_vt_load_attempted
and IsVtInitialized().

+// only once, regardless of the --no-sandbox flag.
+static bool vt_init_attempted = false;
+static bool vt_init_successful = false;
+
 // Size to use for NALU length headers in AVC format (can be 1, 2, or 4).
 static const int kNALUHeaderLength = 4;
 
@@ -86,6 +91,8 @@ BuildImageConfig(CMVideoDimensions coded_dimensions) {
 // internally. If that happens, the likely solution is to expand the scope of
 // this initialization.
 void InitializeVideoToolbox() {
+  vt_init_attempted = true;
+
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kDisableAcceleratedVideoDecode)) {
     return;
@@ -159,6 +166,8 @@ void InitializeVideoToolbox() {
     content_common_gpu_media::UninitializeVt();
     return;
   }
+
+  vt_init_successful = true;
 }
 
 // Route decoded frame callbacks back into the VTVideoDecodeAccelerator.
@@ -229,7 +238,10 @@ bool VTVideoDecodeAccelerator::Initialize(
   DCHECK(gpu_thread_checker_.CalledOnValidThread());
   client_ = client;
 
-  if (!IsVtInitialized())
+  if (!vt_init_attempted)
+    InitializeVideoToolbox();
+
+  if (!vt_init_successful)
     return false;
 
   // Only H.264 is supported.
@@ -474,8 +486,8 @@ void VTVideoDecodeAccelerator::DecodeTask(
       return;
   }
 
-  // If there are no non-configuration units, drop the bitstream buffer by
-  // returning an empty frame.
+  // If there are no image slices, drop the bitstream buffer by returning an
+  // empty frame.
   if (!data_size) {
     if (!FinishDelayedFrames())
       return;