Reland "Add a utility to format a base::debug::StackTrace for CrashKeyString."

This is a reland of f12be75c
Original change's description:
> Add a utility to format a base::debug::StackTrace for CrashKeyString.
>
> Bug: 598854
> Change-Id: Ie92935f4919e57cae338c33750458c0509a93627
> Reviewed-on: https://chromium-review.googlesource.com/782040
> Commit-Queue: Robert Sesek <rsesek@chromium.org>
> Reviewed-by: Mark Mentovai <mark@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#518381}

Bug: 598854, 787669
Change-Id: I81fef0cba08240ee288d4e3db3c3bcf4ff130219
Reviewed-on: https://chromium-review.googlesource.com/793930Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519727}

components/crash/core/common/BUILD.gn

@@ -15,6 +15,7 @@ group("common") {
 
 static_library("crash_key") {
   sources = [
+    "crash_key.cc",
     "crash_key.h",
   ]
 

components/crash/core/common/crash_key.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/crash/core/common/crash_key.h"
+
+#include "base/format_macros.h"
+#include "base/strings/stringprintf.h"
+
+namespace crash_reporter {
+namespace internal {
+
+std::string FormatStackTrace(const base::debug::StackTrace& trace,
+                             size_t max_length) {
+  size_t count = 0;
+  const void* const* addresses = trace.Addresses(&count);
+
+  std::string value;
+  for (size_t i = 0; i < count; ++i) {
+    std::string address = base::StringPrintf(
+        "0x%" PRIx64, reinterpret_cast<uint64_t>(addresses[i]));
+    if (value.size() + address.size() > max_length)
+      break;
+    value += address + " ";
+  }
+
+  if (!value.empty() && value.back() == ' ') {
+    value.resize(value.size() - 1);
+  }
+
+  return value;
+}
+
+}  // namespace internal
+}  // namespace crash_reporter

components/crash/core/common/crash_key.h

@@ -7,6 +7,9 @@
 
 #include <stdint.h>
 
+#include <string>
+
+#include "base/debug/stack_trace.h"
 #include "base/macros.h"
 #include "base/strings/string_piece.h"
 #include "build/build_config.h"
@@ -171,6 +174,25 @@ class ScopedCrashKeyString {
   DISALLOW_COPY_AND_ASSIGN(ScopedCrashKeyString);
 };
 
+namespace internal {
+// Formats a stack trace into a string whose length will not exceed
+// |max_length|. This function ensures no addresses are truncated when
+// being formatted.
+std::string FormatStackTrace(const base::debug::StackTrace& trace,
+                             size_t max_length);
+}  // namespace internal
+
+// Formats a base::debug::StackTrace as a string of space-separated hexadecimal
+// numbers and stores it in a CrashKeyString.
+// TODO(rsesek): When all clients use Crashpad, traces should become a first-
+// class Annotation type rather than being forced through string conversion.
+template <uint32_t Size>
+void SetCrashKeyStringToStackTrace(CrashKeyString<Size>* key,
+                                   const base::debug::StackTrace& trace) {
+  std::string trace_string = internal::FormatStackTrace(trace, Size);
+  key->Set(trace_string);
+}
+
 // Initializes the crash key subsystem if it is required.
 void InitializeCrashKeys();
 

components/crash/core/common/crash_key_unittest.cc

@@ -4,6 +4,8 @@
 
 #include "components/crash/core/common/crash_key.h"
 
+#include "base/debug/stack_trace.h"
+#include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace crash_reporter {
@@ -27,5 +29,54 @@ TEST_F(CrashKeyStringTest, ScopedCrashKeyString) {
   EXPECT_FALSE(key.is_set());
 }
 
+TEST_F(CrashKeyStringTest, FormatStackTrace) {
+  const uintptr_t addresses[] = {
+      0x0badbeef, 0x77778888, 0xabc, 0x000ddeeff, 0x12345678,
+  };
+  base::debug::StackTrace trace(reinterpret_cast<const void* const*>(addresses),
+                                arraysize(addresses));
+
+  std::string too_small = internal::FormatStackTrace(trace, 3);
+  EXPECT_EQ(0u, too_small.size());
+
+  std::string one_value = internal::FormatStackTrace(trace, 16);
+  EXPECT_EQ("0xbadbeef", one_value);
+
+  std::string three_values = internal::FormatStackTrace(trace, 30);
+  EXPECT_EQ("0xbadbeef 0x77778888 0xabc", three_values);
+
+  std::string all_values = internal::FormatStackTrace(trace, 128);
+  EXPECT_EQ("0xbadbeef 0x77778888 0xabc 0xddeeff 0x12345678", all_values);
+}
+
+#if defined(ARCH_CPU_64_BITS)
+TEST_F(CrashKeyStringTest, FormatStackTrace64) {
+  const uintptr_t addresses[] = {
+      0xbaaaabaaaaba, 0x1000000000000000,
+  };
+  base::debug::StackTrace trace(reinterpret_cast<const void* const*>(addresses),
+                                arraysize(addresses));
+
+  std::string too_small = internal::FormatStackTrace(trace, 8);
+  EXPECT_EQ(0u, too_small.size());
+
+  std::string one_value = internal::FormatStackTrace(trace, 20);
+  EXPECT_EQ("0xbaaaabaaaaba", one_value);
+
+  std::string all_values = internal::FormatStackTrace(trace, 35);
+  EXPECT_EQ("0xbaaaabaaaaba 0x1000000000000000", all_values);
+}
+#endif
+
+TEST_F(CrashKeyStringTest, SetStackTrace) {
+  static CrashKeyString<1024> key("test-trace");
+
+  EXPECT_FALSE(key.is_set());
+
+  SetCrashKeyStringToStackTrace(&key, base::debug::StackTrace());
+
+  EXPECT_TRUE(key.is_set());
+}
+
 }  // namespace
 }  // namespace crash_reporter