libgui: Normalize IGraphicBufferConsumer methods

This change modifies IGraphicBufferConsumer such that all synchronous
methods return a status_t and, as such, all outputs are returned by
output parameter rather than return value. It also eliminates the use
of a const char* parameter that SafeInterface can't handle.

Test: m -j + libgui_tests + manual testing
Change-Id: I9bb0e2892492d5e0a3f660bf228834b9ed014539
diff --git a/include/gui/BufferQueueConsumer.h b/include/gui/BufferQueueConsumer.h
index da574ec..1e22d28 100644
--- a/include/gui/BufferQueueConsumer.h
+++ b/include/gui/BufferQueueConsumer.h
@@ -110,7 +110,7 @@
     virtual status_t setMaxAcquiredBufferCount(int maxAcquiredBuffers);
 
     // setConsumerName sets the name used in logging
-    virtual void setConsumerName(const String8& name);
+    status_t setConsumerName(const String8& name) override;
 
     // setDefaultBufferFormat allows the BufferQueue to create
     // GraphicBuffers of a defaultFormat if no format is specified
@@ -135,7 +135,7 @@
     virtual status_t setTransformHint(uint32_t hint);
 
     // Retrieve the sideband buffer stream, if any.
-    virtual sp<NativeHandle> getSidebandStream() const;
+    status_t getSidebandStream(sp<NativeHandle>* outStream) const override;
 
     // See IGraphicBufferConsumer::getOccupancyHistory
     virtual status_t getOccupancyHistory(bool forceFlush,
@@ -145,7 +145,7 @@
     virtual status_t discardFreeBuffers() override;
 
     // dump our state in a String
-    virtual void dumpState(String8& result, const char* prefix) const;
+    status_t dumpState(const String8& prefix, String8* outResult) const override;
 
     // Functions required for backwards compatibility.
     // These will be modified/renamed in IGraphicBufferConsumer and will be