getByte into the actual buffer, not into the byte array struct (#5227)

Also:
- add a test, confirmed failing without these changes
- rename variable to better represent what it is

Author: mikehaney24

Firebase/CoreDiagnostics/FIRCDLibrary/FIRCoreDiagnostics.m

@@ -236,12 +236,12 @@ + (NSString *)deviceModel {
  * @param data The data to copy into the new bytes array.
  */
 pb_bytes_array_t *FIREncodeData(NSData *data) {
-  pb_bytes_array_t *pbBytes = calloc(1, PB_BYTES_ARRAY_T_ALLOCSIZE(data.length));
-  if (pbBytes != NULL) {
-    [data getBytes:pbBytes range:NSMakeRange(0, data.length)];
-    pbBytes->size = (pb_size_t)data.length;
+  pb_bytes_array_t *pbBytesArray = calloc(1, PB_BYTES_ARRAY_T_ALLOCSIZE(data.length));
+  if (pbBytesArray != NULL) {
+    [data getBytes:pbBytesArray->bytes length:data.length];
+    pbBytesArray->size = (pb_size_t)data.length;
   }
-  return pbBytes;
+  return pbBytesArray;
 }
 
 /** Maps a service string to the representative nanopb enum.

GoogleDataTransportCCTSupport/GDTCCTLibrary/GDTCCTNanopbHelpers.m

@@ -43,12 +43,12 @@
 }
 
 pb_bytes_array_t *GDTCCTEncodeData(NSData *data) {
-  pb_bytes_array_t *pbBytes = calloc(1, PB_BYTES_ARRAY_T_ALLOCSIZE(data.length));
-  if (pbBytes != NULL) {
-    [data getBytes:pbBytes range:NSMakeRange(0, data.length)];
-    pbBytes->size = (pb_size_t)data.length;
+  pb_bytes_array_t *pbBytesArray = calloc(1, PB_BYTES_ARRAY_T_ALLOCSIZE(data.length));
+  if (pbBytesArray != NULL) {
+    [data getBytes:pbBytesArray->bytes length:data.length];
+    pbBytesArray->size = (pb_size_t)data.length;
   }
-  return pbBytes;
+  return pbBytesArray;
 }
 
 #pragma mark - CCT object constructors

GoogleDataTransportCCTSupport/GDTCCTTests/Unit/GDTCCTNanopbHelpersTest.m

@@ -161,4 +161,15 @@ - (void)testEncodingProtoAboveDefaultOSThreshold {
   pb_release(gdt_cct_BatchedLogRequest_fields, &batch);
 }
 
+- (void)testSimpleByteEncodingConsistency {
+  NSData *data = [@"Simple." dataUsingEncoding:NSUTF8StringEncoding];
+  pb_bytes_array_t *bytesArray = GDTCCTEncodeData(data);
+  XCTAssertEqual(bytesArray->size, data.length);
+  XCTAssertTrue(bytesArray->bytes);
+  XCTAssertEqualObjects([[NSString alloc] initWithBytes:bytesArray->bytes
+                                                 length:bytesArray->size
+                                               encoding:NSUTF8StringEncoding],
+                        @"Simple.");
+}
+
 @end