Add MMAP Audio Balance

Similar to adding Mono audio, this cl adds the audio balance settings
to MMAP Audio.

Bug:209521805
Test: Settings -> Accessibility -> Audio Adjustment -> Audio Balance
Use OboeTester and play outputs with various settings on the slider

Change-Id: I3269f6fe39b5f720da69739c49eb787e57f93b0a
diff --git a/media/libaaudio/src/client/AAudioFlowGraph.h b/media/libaaudio/src/client/AAudioFlowGraph.h
index e719d91..2056b70 100644
--- a/media/libaaudio/src/client/AAudioFlowGraph.h
+++ b/media/libaaudio/src/client/AAudioFlowGraph.h
@@ -23,9 +23,12 @@
 #include <system/audio.h>
 
 #include <aaudio/AAudio.h>
+#include <audio_utils/Balance.h>
 #include <flowgraph/ClipToRange.h>
+#include <flowgraph/ManyToMultiConverter.h>
 #include <flowgraph/MonoBlend.h>
 #include <flowgraph/MonoToMultiConverter.h>
+#include <flowgraph/MultiToManyConverter.h>
 #include <flowgraph/RampLinear.h>
 
 class AAudioFlowGraph {
@@ -37,13 +40,17 @@
      * @param sourceChannelCount
      * @param sinkFormat
      * @param sinkChannelCount
+     * @param useMonoBlend
+     * @param audioBalance
+     * @param channelMask
      * @return
      */
     aaudio_result_t configure(audio_format_t sourceFormat,
                               int32_t sourceChannelCount,
                               audio_format_t sinkFormat,
                               int32_t sinkChannelCount,
-                              bool useMonoBlend);
+                              bool useMonoBlend,
+                              float audioBalance);
 
     void process(const void *source, void *destination, int32_t numFrames);
 
@@ -52,14 +59,27 @@
      */
     void setTargetVolume(float volume);
 
+    /**
+     * @param audioBalance between -1.0 and 1.0
+     */
+    void setAudioBalance(float audioBalance);
+
+    /**
+     * @param numFrames to slowly adjust for volume changes
+     */
     void setRampLengthInFrames(int32_t numFrames);
 
 private:
     std::unique_ptr<flowgraph::FlowGraphSourceBuffered>     mSource;
     std::unique_ptr<flowgraph::MonoBlend>                   mMonoBlend;
-    std::unique_ptr<flowgraph::RampLinear>                  mVolumeRamp;
     std::unique_ptr<flowgraph::ClipToRange>                 mClipper;
     std::unique_ptr<flowgraph::MonoToMultiConverter>        mChannelConverter;
+    std::unique_ptr<flowgraph::ManyToMultiConverter>        mManyToMultiConverter;
+    std::unique_ptr<flowgraph::MultiToManyConverter>        mMultiToManyConverter;
+    std::vector<std::unique_ptr<flowgraph::RampLinear>>     mVolumeRamps;
+    std::vector<float>                                      mPanningVolumes;
+    float                                                   mTargetVolume = 1.0f;
+    android::audio_utils::Balance                           mBalance;
     std::unique_ptr<flowgraph::FlowGraphSink>               mSink;
 };