Media Remoting: UMAs to track session events and measurements.

media/remoting/triggers.h

Index: media/remoting/triggers.h
diff --git a/media/remoting/triggers.h b/media/remoting/triggers.h
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+++ b/media/remoting/triggers.h
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+// Copyright 2017 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.
+
+#ifndef MEDIA_REMOTING_TRIGGERS_H_
+#define MEDIA_REMOTING_TRIGGERS_H_
+
+namespace media {
+namespace remoting {
+
+// Events and conditions that can trigger remoting to start.
+//
+// NOTE: Never re-number or re-use numbers for different triggers. These are
+// used in UMA histograms, and must remain backwards-compatible for all time.
+// However, *do* change START_TRIGGER_MAX to one after the greatest value when
+// adding new ones. Also, don't forget to update histograms.xml!
+enum StartTrigger {
+  UNKNOWN_START_TRIGGER = 0,
+
+  // Local presentation changes.
+  ENTERED_FULLSCREEN = 1,  // The media element became the fullscreen element.
+  BECAME_DOMINANT_CONTENT = 2,  // Element now occupies most of the viewport.
+  ENABLED_BY_PAGE = 3,          // The page re-allowed remote playback.
+
+  // User actions, such as connecting to a receiver or pressing play.
+  SINK_AVAILABLE = 4,  // A receiver (sink) became available.
+  PLAY_COMMAND = 5,    // The media element was issued a play command.
+
+  // Met requirements for playback of the media.
+  SUPPORTED_AUDIO_CODEC = 6,  // Stream began using a supported audio codec.
+  SUPPORTED_VIDEO_CODEC = 7,  // Stream began using a supported video codec.
+  CDM_READY = 8,  // The CDM required for decrypting the content became ready.
+
+  // Change this to the highest value.
+  START_TRIGGER_MAX = 8,
+};
+
+// Events and conditions that can result in a start failure, or trigger remoting
+// to stop.
+//
+// NOTE: Never re-number or re-use numbers for different triggers. These are
+// used in UMA histograms, and must remain backwards-compatible for all time.
+// However, *do* change STOP_TRIGGER_MAX to one after the greatest value when
+// adding new ones. Also, don't forget to update histograms.xml!
+enum StopTrigger {
+  UNKNOWN_STOP_TRIGGER = 0,
+
+  // Normal shutdown triggers.
+  ROUTE_TERMINATED = 1,  // The route to the sink was terminated (user action?).

[xjz, 2017/01/17 05:36:25]

remove ?

[miu, 2017/01/17 21:09:18]

I left it in there because commonly it's the user shutting down the route.
Sometimes, however, it could be due to an error (network cable unplugged). We
have no way of knowing here.

+  MEDIA_ELEMENT_DESTROYED = 2,   // The media element on the page was destroyed.
+  EXITED_FULLSCREEN = 3,         // The media element is no longer fullscreened.
+  BECAME_AUXILIARY_CONTENT = 4,  // Element no longer occupies the viewport.
+  DISABLED_BY_PAGE = 5,  // The web page blocked remoting during a session.
+
+  // Content playback related errors forcing shutdown (or failing start).
+  START_RACE = 6,  // Multiple remoting sessions attempted to start.
+  UNSUPPORTED_AUDIO_CODEC = 7,  // Stream began using an unsupported codec.

[xjz, 2017/01/17 05:36:25]

nit: s/codec/audio codec

[miu, 2017/01/17 21:09:18]

Done (80 chars is hard).

+  UNSUPPORTED_VIDEO_CODEC = 8,  // Stream began using an unsupported codec.

[xjz, 2017/01/17 05:36:25]

nit: s/code/video codec

[miu, 2017/01/17 21:09:20]

Done.

+  DECRYPTION_ERROR = 9,  // Could not decrypt content or CDM was destroyed.
+  RECEIVER_INITIALIZE_FAILED = 10,  // The receiver reported a failed init.
+  RECEIVER_PIPELINE_ERROR = 11,  // The media pipeline on the receiver error'ed.
+
+  // Environmental errors forcing shutdown.
+  FRAME_DROP_RATE_HIGH = 12,  // The receiver was dropping too many frames.
+  PACING_TOO_SLOWLY = 13,     // Play-out was too slow, indicating bottlenecks.
+
+  // Communications errors forcing shutdown.
+  PEERS_OUT_OF_SYNC = 14,  // The local state disagrees with the remote.
+  RPC_INVALID = 15,        // An RPC field value is missing or has bad data.
+  DATA_PIPE_CREATE_ERROR = 16,  // Mojo data pipe creation failed (OOM?).

[xjz, 2017/01/17 05:36:25]

ooc: Is OOM the only reason for this error?

[miu, 2017/01/17 21:09:18]

No. It could be due to any weird OS issue (or impl bug). But, most commonly, I
would assume the create fails because shared memory cannot be allocated.

+  MOJO_PIPE_ERROR = 17,         // Mojo message/data pipe operation failed.
+
+  // Change this to the highest value.
+  STOP_TRIGGER_MAX = 17,
+};
+
+}  // namespace remoting
+}  // namespace media
+
+#endif  // MEDIA_REMOTING_TRIGGERS_H_