Mojo interfaces needed for switching audio rendering stream creation and closing from IPC to Mojo

media/mojo/interfaces/media_types.mojom

Index: media/mojo/interfaces/media_types.mojom
diff --git a/media/mojo/interfaces/media_types.mojom b/media/mojo/interfaces/media_types.mojom
index 2c8a39c21c170cfc2570eafb9424121c1c8f12b3..78ef6ed9081d6cbb0b33070b8402f9a494e3de23 100644
--- a/media/mojo/interfaces/media_types.mojom
+++ b/media/mojo/interfaces/media_types.mojom
@@ -6,6 +6,15 @@ module media.interfaces;
 
 import "ui/mojo/geometry/geometry.mojom";
 
+// See media/audio/audio_parameters.h for descriptions.
+// Kept in sync with media::AudioParameters::Format via static_asserts.
+enum AudioFormat {
+  AUDIO_PCM_LINEAR = 0,
+  AUDIO_PCM_LOW_LATENCY,
+  AUDIO_FAKE,
+  AUDIO_FORMAT_LAST = AUDIO_FAKE,
+};
+
 // See media/base/buffering_state.h for descriptions.
 // Kept in sync with media::BufferingState via static_asserts.
 enum BufferingState {
@@ -185,6 +194,19 @@ enum CipherMode {
   MAX = AES_CBC
 };
 
+// This defines a mojo transport format for media::AudioParameters.
+// See media/base/audio_parameters.h for description.
+struct AudioParameters {
+  AudioFormat format;
+  ChannelLayout channel_layout;
+  int32 channels;
+  int32 sample_rate;
+  int32 bits_per_sample;

[miu, 2016/05/05 20:16:39]

Drive-by question: Is bits_per_sample really needed? If all audio data is
transferred in planar float format, this field is irrelevant.

[rchtara, 2016/05/06 08:57:33]

No sure about that: it's set here for example:
https://code.google.com/p/chromium/codesearch#chromium/src/media/base/audio_p...
So it's needed.

I tried to keep here the structure  of AudioParameters in audio_parameters.h as
much as I can: we are going to use this mojo structure when we are going to
mojofy the AudioMsg_NotifyDeviceAuthorized and probably later when mojofying
other audio staffs.

They are many references to the AudioParameters (1451 exactly) so, I think if
you want to remove bits_per_sample, this could be better done in a separate cl.

[DaleCurtis, 2016/05/06 17:31:19]

It's irrelevant, so I'd drop it and just add a DCHECK that you only receive
bits_per_sample==16 on the renderer side in case someone ever changes it.

[miu, 2016/05/06 18:06:21]

BTW--I filed a "FixIt/Polish" bug for this (explains more about why this is not
needed): https://crbug.com/609890

[rchtara, 2016/05/10 16:04:52]

great, I will do that in the second cl.

[rchtara, 2016/05/10 16:04:52]

great

+  int32 frames_per_buffer;
+  int32 effects;
+  // TODO(rchtara): add |mic_positions| if needed.
+};
+
 // This defines a mojo transport format for media::EncryptionScheme::Pattern
 // See media/base/encryption_scheme.h for description.
 struct Pattern {