FramebufferSurface: fix for limitFramebufferSize

This CL fixes limitFramebufferSize and adds a test for the
broken use case. Also limitFramebufferSize is renamed to
limitSize  because "Framebuffer" is implied by the class
name. The implementation is moved to a static
limitSizeInternal which can be tested more easily.

Bug: 180908183
Test: atest FramebufferSurfaceTest
Change-Id: Ic094b36fef6f9a17c87ec95a6c3f5f0a09c99d2f
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 3c1b9d8..9f94c73 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -55,6 +55,7 @@
         "EventThreadTest.cpp",
         "FpsReporterTest.cpp",
         "FpsTest.cpp",
+        "FramebufferSurfaceTest.cpp",
         "FrameTimelineTest.cpp",
         "HWComposerTest.cpp",
         "OneShotTimerTest.cpp",