Add experiments info to crash dumps.

chrome/app/breakpad_win_unittest.cc

+// Copyright (c) 2012 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 "base/metrics/field_trial.h"
+#include "base/stringprintf.h"
+#include "breakpad/src/client/windows/common/ipc_protocol.h"
+#include "chrome/app/breakpad_win.h"
+#include "chrome/common/child_process_logging.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+class ChromeAppBreakpadTest : public testing::Test {
+ public:
+  ChromeAppBreakpadTest()
+      : custom_info_(testing::TestGetCustomInfo()),
+        num_experiments_index_(0) {
+    while (num_experiments_index_ < custom_info_->count) {
+      if (!wcsncmp(custom_info_->entries[num_experiments_index_].name,
+          kNumExperiments, kNumExperimentsSize + 1)) {
+        break;
+      }
+      ++num_experiments_index_;
+    }
+    // We need room for the kMaxReportedExperimentChunks experiment chunks.
+    EXPECT_GE(custom_info_->count,
+        num_experiments_index_ + kMaxReportedExperimentChunks);
+  }
+
+ protected:
+  typedef std::vector<base::FieldTrial::NameGroupId> Experiments;
+  void ValidateExperimentChunks(const Experiments& experiments) {
+    testing::TestUpdateExperiments();
+    EXPECT_STREQ(base::StringPrintf(L"%d", experiments.size()).c_str(),
+                 custom_info_->entries[num_experiments_index_].value);
+    // We make a copy of the array that we empty as we find the experiments.
+    Experiments experiments_left(experiments);
+    for (int i = 1; i <= kMaxReportedExperimentChunks; ++i) {
+      EXPECT_STREQ(base::StringPrintf(L"experiment-chunk-%i", i).c_str(),
+                   custom_info_->entries[num_experiments_index_ + i].name);

[robertshield, 2012/03/14 13:51:48]

is there an off-by-one here and in the two places below, the |i| offset starts
at 1?

[MAD, 2012/03/15 22:37:36]

No, it's on purpose, we want the string to be 1 base and not 0 based. OK?

[robertshield, 2012/03/20 19:24:31]

That's unconventional enough to merit a comment about the whats and the whys :-)

Also, in breakpad_win.cc, it looks like we iterate over an entries array from 0
to kMaxReportedExperimentChunks - 1, rather than 1 to
kMaxReportedExperimentChunks. Why the discrepancy? (I'm sure all will become
clear with a comment :-))

+      if (experiments_left.empty()) {
+        // All other slots should be empty.
+        EXPECT_STREQ(L"",
+                     custom_info_->entries[num_experiments_index_ + i].value);
+      } else {
+        // We can't guarantee the order, so we must search for them all.
+        Experiments::const_iterator experiment = experiments_left.begin();
+        while (experiment != experiments_left.end()) {
+          std::wstring experiment_str = base::StringPrintf(
+              L"%x-%x", experiment->name, experiment->group);
+          if (wcsstr(custom_info_->entries[num_experiments_index_ + i].value,
+                     experiment_str.c_str())) {
+            experiment = experiments_left.erase(experiment);
+          } else {
+            ++experiment;
+          }
+        }
+      }
+    }
+    EXPECT_TRUE(experiments_left.empty());
+  }
+
+ private:
+  static const wchar_t* kNumExperiments;
+  static const size_t kNumExperimentsSize;
+  google_breakpad::CustomClientInfo* custom_info_;
+  size_t num_experiments_index_;
+};
+
+const wchar_t* ChromeAppBreakpadTest::kNumExperiments = L"num-experiments";
+const size_t ChromeAppBreakpadTest::kNumExperimentsSize =
+    wcslen(ChromeAppBreakpadTest::kNumExperiments);
+
+TEST_F(ChromeAppBreakpadTest, ExperimentList) {
+  base::FieldTrialList field_trial_list("ABCDE");
+  base::FieldTrial* trial = base::FieldTrialList::CreateFieldTrial("All", "To");
+  base::FieldTrial::NameGroupId name_group_id;
+  trial->GetNameGroupId(&name_group_id);
+  Experiments experiments;
+  experiments.push_back(name_group_id);
+  ValidateExperimentChunks(experiments);
+
+  trial = base::FieldTrialList::CreateFieldTrial("There", "You Are");
+  trial->GetNameGroupId(&name_group_id);
+  experiments.push_back(name_group_id);
+  ValidateExperimentChunks(experiments);
+
+  trial = base::FieldTrialList::CreateFieldTrial("Peter", "Sellers");
+  trial->GetNameGroupId(&name_group_id);
+  experiments.push_back(name_group_id);
+  ValidateExperimentChunks(experiments);
+
+  trial = base::FieldTrialList::CreateFieldTrial("Eat me", "Drink me");
+  trial->GetNameGroupId(&name_group_id);
+  experiments.push_back(name_group_id);
+  ValidateExperimentChunks(experiments);
+}