1 files changed, 86 insertions, 6 deletions

diff --git a/base/metrics/histogram.cc b/base/metrics/histogram.cc
index ea4f816..7feacdb 100644
--- a/base/metrics/histogram.cc
+++ b/base/metrics/histogram.cc
@@ -154,10 +154,22 @@ HistogramBase* Histogram::Factory::Build() {
   ImportPersistentHistograms();
 
   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name_);
+
+  // crbug.com/588946 debugging. See comment at end of function.
+  const BucketRanges* created_ranges =
+      reinterpret_cast<const BucketRanges*>(0xDEADBEEF);
+  const BucketRanges* registered_ranges =
+      reinterpret_cast<const BucketRanges*>(0xDEADBEEF);
+  HistogramBase* tentative_histogram =
+      reinterpret_cast<HistogramBase*>(0xDEADBEEF);
+  PersistentMemoryAllocator* allocator =
+      reinterpret_cast<PersistentMemoryAllocator*>(0xDEADBEEF);
+  PersistentMemoryAllocator::Reference histogram_ref = 0xDEADBEEF;
+
   if (!histogram) {
     // To avoid racy destruction at shutdown, the following will be leaked.
-    const BucketRanges* created_ranges = CreateRanges();
-    const BucketRanges* registered_ranges =
+    created_ranges = CreateRanges();
+    registered_ranges =
         StatisticsRecorder::RegisterOrDeleteDuplicateRanges(created_ranges);
 
     // In most cases, the bucket-count, minimum, and maximum values are known
@@ -170,15 +182,17 @@ HistogramBase* Histogram::Factory::Build() {
       minimum_ = registered_ranges->range(1);
       maximum_ = registered_ranges->range(bucket_count_ - 1);
     }
+    CHECK_LT(0, minimum_);
+    CHECK_LT(0, maximum_);
 
     // Try to create the histogram using a "persistent" allocator. As of
     // 2015-01-14, the availability of such is controlled by a base::Feature
     // that is off by default. If the allocator doesn't exist or if
     // allocating from it fails, code below will allocate the histogram from
     // the process heap.
-    PersistentMemoryAllocator::Reference histogram_ref = 0;
-    HistogramBase* tentative_histogram = nullptr;
-    PersistentMemoryAllocator* allocator =
+    histogram_ref = 0;
+    tentative_histogram = nullptr;
+    allocator =
         GetPersistentHistogramMemoryAllocator();
     if (allocator) {
       flags_ |= HistogramBase::kIsPersistent;
@@ -191,6 +205,12 @@ HistogramBase* Histogram::Factory::Build() {
           registered_ranges,
           flags_,
           &histogram_ref);
+      CHECK_LT(0, minimum_);
+      CHECK_LT(0, maximum_);
+      CHECK_EQ(minimum_,
+               static_cast<Histogram*>(tentative_histogram)->declared_min_);
+      CHECK_EQ(maximum_,
+               static_cast<Histogram*>(tentative_histogram)->declared_max_);
     }
 
     // Handle the case where no persistent allocator is present or the
@@ -200,6 +220,12 @@ HistogramBase* Histogram::Factory::Build() {
       DCHECK(!allocator);  // Shouldn't have failed.
       flags_ &= ~HistogramBase::kIsPersistent;
       tentative_histogram = HeapAlloc(registered_ranges);
+      CHECK_LT(0, minimum_);
+      CHECK_LT(0, maximum_);
+      CHECK_EQ(minimum_,
+               static_cast<Histogram*>(tentative_histogram)->declared_min_);
+      CHECK_EQ(maximum_,
+               static_cast<Histogram*>(tentative_histogram)->declared_max_);
     }
 
     FillHistogram(tentative_histogram);
@@ -214,6 +240,15 @@ HistogramBase* Histogram::Factory::Build() {
   }
 
   DCHECK_EQ(histogram_type_, histogram->GetHistogramType());
+  bool bad_args = false;
+  HistogramBase* existing_histogram = histogram;
+  HistogramType existing_type = histogram->GetHistogramType();
+  const char* existing_name = histogram->histogram_name().c_str();
+  Sample existing_minimum = static_cast<Histogram*>(histogram)->declared_min_;
+  Sample existing_maximum = static_cast<Histogram*>(histogram)->declared_max_;
+  uint32_t existing_bucket_count =
+    static_cast<Histogram*>(histogram)->bucket_count();
+
   if (bucket_count_ != 0 &&
       !histogram->HasConstructionArguments(minimum_, maximum_, bucket_count_)) {
     // The construction arguments do not match the existing histogram.  This can
@@ -223,8 +258,45 @@ HistogramBase* Histogram::Factory::Build() {
     // on dereference, but extension/Pepper APIs will guard against NULL and not
     // crash.
     DLOG(ERROR) << "Histogram " << name_ << " has bad construction arguments";
-    return nullptr;
+    bad_args = true;
+    histogram = nullptr;
+  }
+
+#if !DCHECK_IS_ON()  // Don't affect tests, only release builds.
+  // For the moment, crash here so that collected crash reports have access
+  // to the construction values in order to figure out why this is failing.
+  // TODO(bcwhite): Remove this once crbug.com/588946 is resolved. Also remove
+  // from beta-branch because we don't want crashes due to misbehaving
+  // extensions (see comment above).
+  if (!histogram) {
+    HistogramType histogram_type = histogram_type_;
+    HistogramBase::Sample minimum = minimum_;
+    HistogramBase::Sample maximum = maximum_;
+    uint32_t bucket_count = bucket_count_;
+    int32_t flags = flags_;
+    CHECK(histogram) << name_ << ": bad-args=" << bad_args;
+    base::debug::Alias(&histogram_type);
+    base::debug::Alias(&minimum);
+    base::debug::Alias(&maximum);
+    base::debug::Alias(&bucket_count);
+    base::debug::Alias(&flags);
+    base::debug::Alias(&created_ranges);
+    base::debug::Alias(&registered_ranges);
+    base::debug::Alias(&histogram_ref);
+    base::debug::Alias(&tentative_histogram);
+    base::debug::Alias(&allocator);
+    base::debug::Alias(&tentative_histogram);
   }
+#endif
+
+  // Down here so vars are always "used".
+  base::debug::Alias(&bad_args);
+  base::debug::Alias(&existing_histogram);
+  base::debug::Alias(&existing_type);
+  base::debug::Alias(&existing_name);
+  base::debug::Alias(&existing_minimum);
+  base::debug::Alias(&existing_maximum);
+  base::debug::Alias(&existing_bucket_count);
   return histogram;
 }
 
@@ -486,8 +558,12 @@ Histogram::Histogram(const std::string& name,
     bucket_ranges_(ranges),
     declared_min_(minimum),
     declared_max_(maximum) {
+  CHECK_LT(0, minimum);
+  CHECK_LT(0, maximum);
   if (ranges)
     samples_.reset(new SampleVector(HashMetricName(name), ranges));
+  CHECK_EQ(minimum, declared_min_);
+  CHECK_EQ(maximum, declared_max_);
 }
 
 Histogram::Histogram(const std::string& name,
@@ -503,12 +579,16 @@ Histogram::Histogram(const std::string& name,
     bucket_ranges_(ranges),
     declared_min_(minimum),
     declared_max_(maximum) {
+  CHECK_LT(0, minimum);
+  CHECK_LT(0, maximum);
   if (ranges) {
     samples_.reset(new SampleVector(HashMetricName(name),
                                     counts, counts_size, meta, ranges));
     logged_samples_.reset(new SampleVector(samples_->id(), logged_counts,
                                            counts_size, logged_meta, ranges));
   }
+  CHECK_EQ(minimum, declared_min_);
+  CHECK_EQ(maximum, declared_max_);
 }
 
 Histogram::~Histogram() {