Cast: add UMA for video encode accelerator initialization result.

media/cast/sender/external_video_encoder.cc

Index: media/cast/sender/external_video_encoder.cc
diff --git a/media/cast/sender/external_video_encoder.cc b/media/cast/sender/external_video_encoder.cc
index e3abecd4074cb183290a92b3b4b77b06c03b8f05..4c20f8565639855a40f3e198c96dfaab581d1926 100644
--- a/media/cast/sender/external_video_encoder.cc
+++ b/media/cast/sender/external_video_encoder.cc
@@ -9,6 +9,7 @@
 #include "base/memory/scoped_vector.h"
 #include "base/memory/shared_memory.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram.h"
 #include "media/base/video_frame.h"
 #include "media/base/video_util.h"
 #include "media/cast/cast_defines.h"
@@ -114,12 +115,16 @@ class LocalVideoEncodeAcceleratorClient
     }
     max_frame_rate_ = video_config.max_frame_rate;
 
-    if (!video_encode_accelerator_->Initialize(
-            media::VideoFrame::I420,
-            gfx::Size(video_config.width, video_config.height),
-            output_profile,
-            video_config.start_bitrate,
-            this)) {
+    bool result = video_encode_accelerator_->Initialize(
+        media::VideoFrame::I420,
+        gfx::Size(video_config.width, video_config.height),
+        output_profile,
+        video_config.start_bitrate,
+        this);
+
+    UMA_HISTOGRAM_BOOLEAN("Cast.Sender.VideoEncodeAcceleratorInitializeSuccess",
+                          result);
+    if (!result) {
       NotifyError(VideoEncodeAccelerator::kInvalidArgumentError);
       return;
     }