Use String8/16 c_str [graphics]

Bug: 295394788
Test: make checkbuild
Change-Id: I69aa06b109c2f40ecf40441cbbb0dfa3e1aa99a1
Merged-In: I69aa06b109c2f40ecf40441cbbb0dfa3e1aa99a1
diff --git a/libs/gui/tests/SurfaceTextureFBO_test.cpp b/libs/gui/tests/SurfaceTextureFBO_test.cpp
index f34561f..ccd0e59 100644
--- a/libs/gui/tests/SurfaceTextureFBO_test.cpp
+++ b/libs/gui/tests/SurfaceTextureFBO_test.cpp
@@ -59,7 +59,7 @@
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
 
     for (int i = 0; i < 4; i++) {
-        SCOPED_TRACE(String8::format("frame %d", i).string());
+        SCOPED_TRACE(String8::format("frame %d", i).c_str());
 
         ASSERT_EQ(NO_ERROR, native_window_dequeue_buffer_and_wait(mANW.get(),
                 &anb));