Add UMA to track software fallback in VTVideoDecodeAccelerator.

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 9a91c9c0f1400ac5f61045a74f3dc5309f7e8164..0cfc6b3e60ee54db67489cd668320fc9198a9b25 100644
--- a/content/common/gpu/media/vt_video_decode_accelerator.cc
+++ b/content/common/gpu/media/vt_video_decode_accelerator.cc
@@ -12,6 +12,7 @@
 #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"
@@ -318,7 +319,8 @@ bool VTVideoDecodeAccelerator::ConfigureDecoder() {
   base::ScopedCFTypeRef<CFMutableDictionaryRef> image_config(
       BuildImageConfig(coded_dimensions));
 
-  // TODO(sandersd): Does the old session need to be flushed first?
+  if (!FinishDelayedFrames())

[Pawel Osciak, 2014/12/02 01:21:51]

This is I think not related to this CL?

[sandersd (OOO until July 31), 2014/12/02 01:25:31]

Done.

+    return false;
   session_.reset();
   status = VTDecompressionSessionCreate(
       kCFAllocatorDefault,
@@ -332,6 +334,18 @@ bool VTVideoDecodeAccelerator::ConfigureDecoder() {
     return false;
   }
 
+  // Report whether hardware decode is being used.
+  base::ScopedCFTypeRef<CFBooleanRef> using_hardware;
+  if (VTSessionCopyProperty(
+        session_,
+        // kVTDecompressionPropertyKey_UsingHardwareAcceleratedVideoDecoder
+        CFSTR("UsingHardwareAcceleratedVideoDecoder"),
+        kCFAllocatorDefault,
+        using_hardware.InitializeInto()) == 0) {
+    UMA_HISTOGRAM_BOOLEAN("Media.VTVDA.UsingHardware",
+                          CFBooleanGetValue(using_hardware));
+  }
+
   return true;
 }