AudioRecord::getInputFramesLost() cleanup

Fixed bug that if the binder call failed (for example if the
IAudioFlinger binder is dead), then getInputFramesLost was returning
garbage.  Now it correctly returns zero, which is the error value for
this method.

The type declarations for getInputFramesLost were inconsistent:
a mixture of unsigned int, size_t, and uint32_t.  Now it returns uint32_t
everywhere, which is what the underlying HAL API returns.

Added a FIXME about the side effect behavior.  This will need review
for multi-client.

Change-Id: Ifa2e117a87dbd0c1f2c892a31d1c3dd919bf1a0a
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 6b81c38..2b749fa 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -907,7 +907,7 @@
     virtual String8     getParameters(const String8& keys);
     virtual void        audioConfigChanged_l(int event, int param = 0);
             void        readInputParameters();
-    virtual unsigned int  getInputFramesLost();
+    virtual uint32_t    getInputFramesLost();
 
     virtual status_t addEffectChain_l(const sp<EffectChain>& chain);
     virtual size_t removeEffectChain_l(const sp<EffectChain>& chain);