Expand PrefHashBrowserTest to ensure unloaded profile initialization produces proper hashes.

chrome/browser/prefs/pref_hash_browsertest.cc

Index: chrome/browser/prefs/pref_hash_browsertest.cc
diff --git a/chrome/browser/prefs/pref_hash_browsertest.cc b/chrome/browser/prefs/pref_hash_browsertest.cc
index 1bcc0fd27f0f47d50d9bc44bf6841c8bc2a20d3f..9d433885d72c5daa1e8718daafcb9569f0087983 100644
--- a/chrome/browser/prefs/pref_hash_browsertest.cc
+++ b/chrome/browser/prefs/pref_hash_browsertest.cc
@@ -7,11 +7,16 @@
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
+#include "base/macros.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram_base.h"
+#include "base/metrics/histogram_samples.h"
+#include "base/metrics/statistics_recorder.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string16.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/prefs/pref_hash_store.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_impl.h"
 #include "chrome/browser/profiles/profile_info_cache.h"
@@ -58,6 +63,29 @@ base::FilePath GetUnloadedProfilePath() {
   return base::FilePath();
 }
 
+// Returns the number of times |histogram_name| was reported so far; adding the
+// results of the first 100 buckets (there are only ~14 reporting IDs as of this
+// writting; varies depending on the platform). If |expect_zero| is true, this
+// method will explicitly report IDs that are non-zero for ease of diagnosis.
+int GetTrackedPrefHistogramCount(const char* const histogram_name,

[Bernhard Bauer, 2014/01/30 10:36:53]

Do we actually need both of these const's? I think |histogram_name| itself (i.e.
the variable, not the data behind it) doesn't really need to be const, as it's
local to the method anyway.

[gab, 2014/01/30 14:52:13]

Sure, I like to put const as much as possible, but in this case I agree that the
second const would be like taking "const int" as a parameter which we don't
typically do as it's passed-by-value.

Done.

+                                 bool expect_zero) {
+  const base::HistogramBase* histogram =
+      base::StatisticsRecorder::FindHistogram(histogram_name);
+  if (!histogram)
+    return 0;
+
+  scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
+  int sum = 0;
+  for (int i = 0; i < 100; ++i) {
+    int count_for_id = samples->GetCount(i);
+    sum += count_for_id;
+
+    if (expect_zero)
+      EXPECT_EQ(0, count_for_id) << "Faulty reporting_id: " << i;
+  }
+  return sum;
+}
+
 }  // namespace
 
 typedef InProcessBrowserTest PrefHashBrowserTest;
@@ -126,12 +154,58 @@ IN_PROC_BROWSER_TEST_F(PrefHashBrowserTest,
   ASSERT_EQ(3U, hashes->size());
 
   ProfileManager* profile_manager = g_browser_process->profile_manager();
-  const std::vector<Profile*> loaded_profiles =
-      profile_manager->GetLoadedProfiles();
 
   // Verify that only one profile was loaded. We assume that the unloaded
   // profile is the same one that wasn't loaded in the last launch (i.e., it's
   // the one whose hash store we reset, and the fact that it is now restored is
   // evidence that we restored the hashes of an unloaded profile.).
-  ASSERT_EQ(1U, loaded_profiles.size());
+  ASSERT_EQ(1U, profile_manager->GetLoadedProfiles().size());
+
+  // Loading the first profile should only have produced unchanged reports.
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceChanged", true));
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceCleared", true));
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceInitialized", true));
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceTrustedInitialized", true));
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceMigrated", true));
+  int initial_unchanged_count =
+      GetTrackedPrefHistogramCount("Settings.TrackedPreferenceUnchanged",
+                                   false);
+  EXPECT_GT(initial_unchanged_count, 0);
+
+  // Explicitly load the unloaded profile.
+  const Profile* second_profile =
+      profile_manager->GetProfile(GetUnloadedProfilePath());
+  ASSERT_EQ(2U, profile_manager->GetLoadedProfiles().size());
+
+  // Loading the unexpected profile should only generate unchanged pings; and
+  // should have produced as many of them as loading the first profile.
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceChanged", true));
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceCleared", true));
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceInitialized", true));
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceTrustedInitialized", true));
+  EXPECT_EQ(
+      0, GetTrackedPrefHistogramCount(
+             "Settings.TrackedPreferenceMigrated", true));
+  EXPECT_EQ(
+      initial_unchanged_count * 2,
+      GetTrackedPrefHistogramCount("Settings.TrackedPreferenceUnchanged",
+                                   false));
 }