Add support for single sample metrics.

media/renderers/video_renderer_impl.cc

 // Copyright 2013 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 "media/renderers/video_renderer_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/metrics/single_value_histograms.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_util.h"
 #include "base/time/default_tick_clock.h"
 #include "base/trace_event/trace_event.h"
 #include "media/base/bind_to_current_loop.h"
 #include "media/base/limits.h"
 #include "media/base/media_log.h"
 #include "media/base/media_switches.h"
 #include "media/base/pipeline_status.h"
 #include "media/base/renderer_client.h"
@@ skipping 119 matching lines @@
   DCHECK(task_runner_->BelongsToCurrentThread());
   base::AutoLock auto_lock(lock_);
   DCHECK(stream);
   DCHECK_EQ(stream->type(), DemuxerStream::VIDEO);
   DCHECK(!init_cb.is_null());
   DCHECK(!wall_clock_time_cb.is_null());
   DCHECK(kUninitialized == state_ || kFlushed == state_);
   DCHECK(!was_background_rendering_);
   DCHECK(!time_progressing_);
 
+  std::unique_ptr<base::SingleValueCountsHistogram> metric_1(
+      base::SingleValueHistogramsFactory::Get()
+          ->CreateSingleValueCountsHistogram(
+              "Media.VideoRenderer.CadenceChanges", 1, 10, 10));
+  metric_1->SetSample(7);
+  metric_1->SetSample(9);
+
   ScopedVector<VideoDecoder> decoders = create_video_decoders_cb_.Run();
   video_frame_stream_.reset(
       new VideoFrameStream(task_runner_, std::move(decoders), media_log_));
 
   // Always re-initialize or reset the |gpu_memory_buffer_pool_| in case we are
   // switching between video tracks with incompatible video formats (e.g. 8-bit
   // H.264 to 10-bit H264 or vice versa).
   if (gpu_factories_ &&
       gpu_factories_->ShouldUseGpuMemoryBuffersForVideoFrames()) {
     gpu_memory_buffer_pool_.reset(new GpuMemoryBufferVideoFramePool(
@@ skipping 572 matching lines @@
 
 void VideoRendererImpl::AttemptReadAndCheckForMetadataChanges(
     VideoPixelFormat pixel_format,
     const gfx::Size& natural_size) {
   base::AutoLock auto_lock(lock_);
   CheckForMetadataChanges(pixel_format, natural_size);
   AttemptRead_Locked();
 }
 
 }  // namespace media