Add UMA to track software fallback in 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>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/mac/mac_logging.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/sys_byteorder.h"
 #include "base/thread_task_runner_handle.h"
 #include "content/common/gpu/media/vt_video_decode_accelerator.h"
 #include "content/public/common/content_switches.h"
 #include "media/base/limits.h"
 #include "ui/gl/scoped_binders.h"
 
 using content_common_gpu_media::kModuleVt;
 using content_common_gpu_media::InitializeStubs;
 using content_common_gpu_media::IsVtInitialized;
@@ skipping 300 matching lines @@
       format_,              // video_format_description
       decoder_config,       // video_decoder_specification
       image_config,         // destination_image_buffer_attributes
       &callback_,           // output_callback
       session_.InitializeInto());
   if (status) {
     NOTIFY_STATUS("VTDecompressionSessionCreate()", status);
     return false;
   }
 
+  // Report whether hardware decode is being used.
+  base::ScopedCFTypeRef<CFBooleanRef> using_hardware;
+  if (VTSessionCopyProperty(

[DaleCurtis, 2014/12/02 18:20:22]

Does clang-format bless this alignment? It looks off.

[sandersd (OOO until July 31), 2014/12/02 18:28:28]

Done.

+        session_,
+        // kVTDecompressionPropertyKey_UsingHardwareAcceleratedVideoDecoder
+        CFSTR("UsingHardwareAcceleratedVideoDecoder"),
+        kCFAllocatorDefault,
+        using_hardware.InitializeInto()) == 0) {
+    UMA_HISTOGRAM_BOOLEAN("Media.VTVDA.UsingHardware",

[DaleCurtis, 2014/12/02 18:20:22]

Don't you need to log this for some of the other failures above? Probably not
the session reinitialization ones, but the others may cause early abort which
falls back to the software path.

[sandersd (OOO until July 31), 2014/12/02 18:28:29]

This is the only path with internal software fallback, if it fails before this
the whole VDA fails.

[DaleCurtis, 2014/12/02 18:29:59]

Ahhhh, as posciak@ noted, you definitely need a better CL description then :) I
thought this was tracking global software fallback.

+                          CFBooleanGetValue(using_hardware));
+  }
+
   return true;
 }
 
 void VTVideoDecodeAccelerator::DecodeTask(
     const media::BitstreamBuffer& bitstream,
     Frame* frame) {
   DCHECK(decoder_thread_.message_loop_proxy()->BelongsToCurrentThread());
 
   // Map the bitstream buffer.
   base::SharedMemory memory(bitstream.handle(), true);
@@ skipping 540 matching lines @@
   assigned_bitstream_ids_.clear();
   state_ = STATE_DESTROYING;
   QueueFlush(TASK_DESTROY);
 }
 
 bool VTVideoDecodeAccelerator::CanDecodeOnIOThread() {
   return false;
 }
 
 }  // namespace content