tint->dawn: Shuffle source tree in preperation of merging repos

docs/    -> docs/tint/
fuzzers/ -> src/tint/fuzzers/
samples/ -> src/tint/cmd/
src/     -> src/tint/
test/    -> test/tint/

BUG=tint:1418,tint:1433

Change-Id: Id2aa79f989aef3245b80ef4aa37a27ff16cd700b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80482
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>

src/tint/utils/debugger.cc

diff --git a/src/tint/utils/debugger.cc b/src/tint/utils/debugger.cc
new file mode 100644
index 0000000..aded5b6
--- /dev/null
+++ b/src/tint/utils/debugger.cc
@@ -0,0 +1,63 @@
+// Copyright 2022 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/tint/utils/debugger.h"
+
+#ifdef TINT_ENABLE_BREAK_IN_DEBUGGER
+
+#ifdef _MSC_VER
+#include <Windows.h>
+#elif defined(__linux__)
+#include <signal.h>
+#include <fstream>
+#include <string>
+#endif
+
+#ifdef _MSC_VER
+#define TINT_DEBUGGER_BREAK_DEFINED
+void tint::debugger::Break() {
+  if (::IsDebuggerPresent()) {
+    ::DebugBreak();
+  }
+}
+
+#elif defined(__linux__)
+
+#define TINT_DEBUGGER_BREAK_DEFINED
+void tint::debugger::Break() {
+  // A process is being traced (debugged) if "/proc/self/status" contains a
+  // line with "TracerPid: <non-zero-digit>...".
+  bool is_traced = false;
+  std::ifstream fin("/proc/self/status");
+  std::string line;
+  while (!is_traced && std::getline(fin, line)) {
+    const char kPrefix[] = "TracerPid:\t";
+    static constexpr int kPrefixLen = sizeof(kPrefix) - 1;
+    if (line.length() > kPrefixLen &&
+        line.compare(0, kPrefixLen, kPrefix) == 0) {
+      is_traced = line[kPrefixLen] != '0';
+    }
+  }
+
+  if (is_traced) {
+    raise(SIGTRAP);
+  }
+}
+#endif  // platform
+
+#endif  // TINT_ENABLE_BREAK_IN_DEBUGGER
+
+#ifndef TINT_DEBUGGER_BREAK_DEFINED
+void tint::debugger::Break() {}
+#endif