Minor robustness improvements for VTVideoDecodeAccelerator.

content/common/gpu/media/vt_video_decode_accelerator.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 <algorithm>
 
 #include <CoreVideo/CoreVideo.h>
 #include <OpenGL/CGLIOSurface.h>
 #include <OpenGL/gl.h>
 
@@ skipping 614 matching lines @@
   }
 }
 
 // This method may be called on any VideoToolbox thread.
 void VTVideoDecodeAccelerator::Output(
     void* source_frame_refcon,
     OSStatus status,
     CVImageBufferRef image_buffer) {
   if (status) {
     NOTIFY_STATUS("Decoding", status);
-  } else if (CFGetTypeID(image_buffer) != CVPixelBufferGetTypeID()) {
+    return;
+  }
+
+  // The type of |image_buffer| is CVImageBuffer, but we only handle
+  // CVPixelBuffers. This should be guaranteed as we set
+  // kCVPixelBufferOpenGLCompatibilityKey in |image_config|.
+  //
+  // Sometimes, for unknown reasons (http://crbug.com/453050), |image_buffer| is
+  // NULL, which causes CFGetTypeID() to crash. While the rest of the code would
+  // smoothly handle NULL as a dropped frame, we choose to fail permanantly here
+  // until the issue is better understood.
+  if (!image_buffer || CFGetTypeID(image_buffer) != CVPixelBufferGetTypeID()) {
     DLOG(ERROR) << "Decoded frame is not a CVPixelBuffer";
     NotifyError(PLATFORM_FAILURE);
-  } else {
-    Frame* frame = reinterpret_cast<Frame*>(source_frame_refcon);
-    frame->image.reset(image_buffer, base::scoped_policy::RETAIN);
-    gpu_task_runner_->PostTask(FROM_HERE, base::Bind(
-        &VTVideoDecodeAccelerator::DecodeDone, weak_this_, frame));
+    return;
   }
+
+  Frame* frame = reinterpret_cast<Frame*>(source_frame_refcon);
+  frame->image.reset(image_buffer, base::scoped_policy::RETAIN);
+  gpu_task_runner_->PostTask(FROM_HERE, base::Bind(
+      &VTVideoDecodeAccelerator::DecodeDone, weak_this_, frame));
 }
 
 void VTVideoDecodeAccelerator::DecodeDone(Frame* frame) {
   DCHECK(gpu_thread_checker_.CalledOnValidThread());
   DCHECK_EQ(1u, pending_frames_.count(frame->bitstream_id));
   Task task(TASK_FRAME);
   task.frame = pending_frames_[frame->bitstream_id];
   pending_frames_.erase(frame->bitstream_id);
   task_queue_.push(task);
   ProcessWorkQueues();
@@ skipping 54 matching lines @@
   } else {
     client_->DismissPictureBuffer(picture_id);
   }
 }
 
 void VTVideoDecodeAccelerator::ProcessWorkQueues() {
   DCHECK(gpu_thread_checker_.CalledOnValidThread());
   switch (state_) {
     case STATE_DECODING:
       // TODO(sandersd): Batch where possible.
-      while (ProcessReorderQueue() || ProcessTaskQueue());
+      while (state_ == STATE_DECODING) {
+        if (!ProcessReorderQueue() && !ProcessTaskQueue())
+          break;
+      }
       return;
 
     case STATE_ERROR:
       // Do nothing until Destroy() is called.
       return;
 
     case STATE_DESTROYING:
       // Drop tasks until we are ready to destruct.
       while (!task_queue_.empty()) {
         if (task_queue_.front().type == TASK_DESTROY) {
@@ skipping 212 matching lines @@
   assigned_bitstream_ids_.clear();
   state_ = STATE_DESTROYING;
   QueueFlush(TASK_DESTROY);
 }
 
 bool VTVideoDecodeAccelerator::CanDecodeOnIOThread() {
   return false;
 }
 
 }  // namespace content