Simplify AudioRecord::getInputFramesLost()

This also fixes a benign race in reading mActive without a lock.

Change-Id: I19e953d4f275e5c266ca1ca3fece7b6c02ad1707
diff --git a/media/libmedia/AudioRecord.cpp b/media/libmedia/AudioRecord.cpp
index f8813c9..01ce2a4 100644
--- a/media/libmedia/AudioRecord.cpp
+++ b/media/libmedia/AudioRecord.cpp
@@ -432,10 +432,8 @@
 
 unsigned int AudioRecord::getInputFramesLost() const
 {
-    if (mActive)
-        return AudioSystem::getInputFramesLost(mInput);
-    else
-        return 0;
+    // no need to check mActive, because if inactive this will return 0, which is what we want
+    return AudioSystem::getInputFramesLost(mInput);
 }
 
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