cbor: Fix typedef struct naming for new CrOS Clang updates

New Clang update reports new warnings when C++ code provides
anonymous typedef structs. The suggested solution is to either add
a tag to the name or use C++-style struct.
This patch fixes the warnings for the next toolchain update.

Bug: 1068297
Test: Tested on Chrome OS
Change-Id: I6863bc10d9094497b0d634ddee04891df8372906
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2144413Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Tiancong Wang <tcwang@google.com>
Cr-Commit-Position: refs/heads/master@{#758025}

components/cbor/writer_unittest.cc

@@ -16,10 +16,10 @@
 namespace cbor {
 
 TEST(CBORWriterTest, TestWriteUint) {
-  typedef struct {
+  struct UintTestCase {
     const int64_t value;
     const base::StringPiece cbor;
-  } UintTestCase;
+  };
 
   static const UintTestCase kUintTestCases[] = {
       // Reminder: must specify length when creating string pieces
@@ -76,10 +76,10 @@ TEST(CBORWriterTest, TestWriteNegativeInteger) {
 }
 
 TEST(CBORWriterTest, TestWriteBytes) {
-  typedef struct {
+  struct BytesTestCase {
     const std::vector<uint8_t> bytes;
     const base::StringPiece cbor;
-  } BytesTestCase;
+  };
 
   static const BytesTestCase kBytesTestCases[] = {
       {{}, base::StringPiece("\x40")},
@@ -94,10 +94,10 @@ TEST(CBORWriterTest, TestWriteBytes) {
 }
 
 TEST(CBORWriterTest, TestWriteString) {
-  typedef struct {
+  struct StringTestCase {
     const std::string string;
     const base::StringPiece cbor;
-  } StringTestCase;
+  };
 
   static const StringTestCase kStringTestCases[] = {
       {"", base::StringPiece("\x60")},