Modifications to audio_hal for Android@Home.

This is a squashed merge of the following changes:

Commit f560da61a5e128ca9f82f7fe939afcf1f09188c7
Author: John Grossman <johngro@google.com>
Date:   Thu Aug 11 15:34:55 2011 -0700

    Fill out a missing entry in the audio HAL function table.

    The entry for get_initial_master_volume was missing from the non-legacy audio
    HAL and needs to be filled out.  Also fix up the order of the comments
    describing the get_initial_master_volume method.

    Change-Id: I87d5415ef92611497a6dab4c657fc00367c4d80b

commit cea82facb63fd237a4ea6fb770605fcb500850ff
Author: Jason Simmons <jsimmons@google.com>
Date:   Thu Jun 16 14:24:24 2011 -0700

    Define a replacement for getSampleDelta that returns a DMA start time and count of samples queued

    Change-Id: I2d13f57b5a8c5b97fb3aa0a90834ce91c56864ef

commit 60a9acd7eee470a8d870218e8be618bfa3be15a5
Author: Mike J. Chen <mjchen@google.com>
Date:   Tue Jun 7 09:13:23 2011 -0700

    Add Android@Home extensions to new Audio HAL interface.

    Change-Id: I3ea4676d4b7d2afd78a5a7a7003ad5c437276d05
    Signed-off-by: Mike J. Chen <mjchen@google.com>

Change-Id: I09f3756d12a1ce4f9af39610ed857890742a72df
Signed-off-by: Mike J. Chen <mjchen@google.com>
Signed-off-by: John Grossman <johngro@google.com>

Conflicts:

	include/hardware/audio.h
	modules/audio/audio_hw.c
diff --git a/include/hardware/audio.h b/include/hardware/audio.h
index fa34467..1e68cd1 100644
--- a/include/hardware/audio.h
+++ b/include/hardware/audio.h
@@ -184,6 +184,14 @@
      */
     int (*get_render_position)(const struct audio_stream_out *stream,
                                uint32_t *dsp_frames);
+
+    /**
+     * get the local time at which the next write to the audio driver will be
+     * presented
+     */
+    int (*get_next_write_timestamp)(const struct audio_stream_out *stream,
+                                    int64_t *timestamp);
+
 };
 typedef struct audio_stream_out audio_stream_out_t;
 
@@ -272,6 +280,15 @@
     int (*set_master_volume)(struct audio_hw_device *dev, float volume);
 
     /**
+     * Get the current master volume value for the HAL, if the HAL supports
+     * master volume control.  AudioFlinger will query this value from the
+     * primary audio HAL when the service starts and use the value for setting
+     * the initial master volume across all HALs.  HALs which do not support
+     * this method should may leave it set to NULL.
+     */
+    int (*get_master_volume)(struct audio_hw_device *dev, float *volume);
+
+    /**
      * set_mode is called when the audio mode changes. AUDIO_MODE_NORMAL mode
      * is for standard audio playback, AUDIO_MODE_RINGTONE when a ringtone is
      * playing, and AUDIO_MODE_IN_CALL when a call is in progress.