gpu: Fix some context lost marking glitches+leaks and add UMA stats

content/renderer/pepper/pepper_video_encoder_host.cc

Index: content/renderer/pepper/pepper_video_encoder_host.cc
diff --git a/content/renderer/pepper/pepper_video_encoder_host.cc b/content/renderer/pepper/pepper_video_encoder_host.cc
index 39292bbcb677031ba002023cf063a0333475a699..7c0b9fd0bf585fbb74b3dcc349f586a225a74176 100644
--- a/content/renderer/pepper/pepper_video_encoder_host.cc
+++ b/content/renderer/pepper/pepper_video_encoder_host.cc
@@ -513,7 +513,7 @@ bool PepperVideoEncoderHost::EnsureGpuChannel() {
     return false;
   }
 
-  command_buffer_->SetChannelErrorCallback(media::BindToCurrentLoop(
+  command_buffer_->SetContextLostCallback(media::BindToCurrentLoop(
       base::Bind(&PepperVideoEncoderHost::NotifyPepperError,
                  weak_ptr_factory_.GetWeakPtr(), PP_ERROR_RESOURCE_FAILED)));
   if (!command_buffer_->Initialize()) {