crashpad: Fix enum vs unsigned -Wsign-compare warnings

Recent Clang versions started taking into account that enums are signed
on Windows when emitting these warnings.

Bug: 792519
Change-Id: I5029cde81ac6f1777ec2317d431d55589b814465
Reviewed-on: https://chromium-review.googlesource.com/811685
Commit-Queue: Mark Mentovai <mark@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522226}

third_party/crashpad/README.chromium

@@ -36,3 +36,4 @@ $ git am --3way --message-id -p4 /tmp/patchdir
 
 Local Modifications:
  - codereview.settings has been excluded.
+ - fix two -Wsign-compare warnings.

third_party/crashpad/crashpad/minidump/minidump_file_writer.cc

@@ -59,7 +59,7 @@ void MinidumpFileWriter::InitializeFromSnapshot(
   DCHECK_EQ(state(), kStateMutable);
   DCHECK_EQ(header_.Signature, 0u);
   DCHECK_EQ(header_.TimeDateStamp, 0u);
-  DCHECK_EQ(header_.Flags, MiniDumpNormal);
+  DCHECK_EQ(static_cast<MINIDUMP_TYPE>(header_.Flags), MiniDumpNormal);
   DCHECK(streams_.empty());
 
   // This time is truncated to an integer number of seconds, not rounded, for

third_party/crashpad/crashpad/minidump/test/minidump_file_writer_test_util.cc

@@ -52,7 +52,7 @@ void VerifyMinidumpHeader(const MINIDUMP_HEADER* header,
   ASSERT_EQ(header->StreamDirectoryRva, streams ? sizeof(MINIDUMP_HEADER) : 0u);
   EXPECT_EQ(header->CheckSum, 0u);
   EXPECT_EQ(header->TimeDateStamp, timestamp);
-  EXPECT_EQ(header->Flags, MiniDumpNormal);
+  EXPECT_EQ(static_cast<MINIDUMP_TYPE>(header->Flags), MiniDumpNormal);
 }
 
 }  // namespace test