Use String8/16 c_str

Bug: 295394788
Test: make checkbuild
Change-Id: I538720d4de2dcc038b417048209782ff605b7e30
diff --git a/media/jni/android_media_ImageReader.cpp b/media/jni/android_media_ImageReader.cpp
index 3b93b07..f7d4825 100644
--- a/media/jni/android_media_ImageReader.cpp
+++ b/media/jni/android_media_ImageReader.cpp
@@ -617,7 +617,7 @@
                         "match the ImageReader's configured buffer format 0x%x.",
                         bufferFormat, ctx->getBufferFormat());
                 jniThrowException(env, "java/lang/UnsupportedOperationException",
-                        msg.string());
+                        msg.c_str());
                 return -1;
             }
         }
@@ -789,7 +789,7 @@
         String8 msg;
         msg.appendFormat("Format 0x%x is opaque, thus not writable, the number of planes (%d)"
                 " must be 0", halReaderFormat, numPlanes);
-        jniThrowException(env, "java/lang/IllegalArgumentException", msg.string());
+        jniThrowException(env, "java/lang/IllegalArgumentException", msg.c_str());
         return NULL;
     }
 
@@ -854,7 +854,7 @@
         String8 msg;
         msg.appendFormat("Format 0x%x is opaque, thus not writable, the number of planes (%d)"
                 " must be 0", halReaderFormat, numPlanes);
-        jniThrowException(env, "java/lang/IllegalArgumentException", msg.string());
+        jniThrowException(env, "java/lang/IllegalArgumentException", msg.c_str());
         return NULL;
     }