Re-enable PrefHashBrowserTest with a few more mitigations and cleanups.

chrome/browser/prefs/tracked/pref_hash_browsertest.cc

Index: chrome/browser/prefs/tracked/pref_hash_browsertest.cc
diff --git a/chrome/browser/prefs/tracked/pref_hash_browsertest.cc b/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
index 6cf4a89d3fa98a2ab9b34409ddd82bc80b69e8c7..202c30a8c9df327bd2e5ca6a7faa8af561a114e8 100644
--- a/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
+++ b/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
@@ -44,7 +44,8 @@
 #endif
 
 #if defined(OS_WIN)
-#include "base/test/test_reg_util_win.h"
+#include "base/win/registry.h"
+#include "chrome/install_static/install_util.h"
 #endif
 
 namespace {
@@ -67,9 +68,25 @@ enum AllowedBuckets {
 
 #if defined(OS_WIN)
 base::string16 GetRegistryPathForTestProfile() {
+  // Cleanup follow-up to http://crbug.com/721245 for the previous location of
+  // this test key which had similar problems (to a lesser extent). It's
+  // redundant but harmless to have multiple callers hit this on the same
+  // machine. TODO(gab): remove this mid-june 2017.
+  base::win::RegKey key;
+  if (key.Open(HKEY_CURRENT_USER, L"SOFTWARE\\Chromium\\PrefHashBrowserTest",
+               KEY_SET_VALUE | KEY_WOW64_32KEY) == ERROR_SUCCESS) {
+    LONG result = key.DeleteKey(L"");
+    EXPECT_TRUE(result == ERROR_SUCCESS || result == ERROR_FILE_NOT_FOUND);
+  }
+
   base::FilePath profile_dir;
   EXPECT_TRUE(PathService::Get(chrome::DIR_USER_DATA, &profile_dir));
-  return L"SOFTWARE\\Chromium\\PrefHashBrowserTest\\" +
+
+  // Use a location under the real PreferenceMACs path so that the backup
+  // cleanup logic in ChromeTestLauncherDelegate::PreSharding() for interrupted
+  // tests covers this test key as well.
+  return install_static::GetRegistryPath() +
+         L"\\PreferenceMACs\\PrefHashBrowserTest\\" +
          profile_dir.BaseName().value();
 }
 #endif
@@ -297,8 +314,6 @@ class PrefHashBrowserTestBase
   void TearDown() override {
 #if defined(OS_WIN)
     // When done, delete the Registry key to avoid polluting the registry.
-    // TODO(proberge): it would be nice to delete keys from interrupted tests
-    // as well.
     if (!IsPRETest()) {
       base::string16 registry_key = GetRegistryPathForTestProfile();
       base::win::RegKey key;
@@ -519,9 +534,7 @@ class PrefHashBrowserTestUnchangedDefault : public PrefHashBrowserTestBase {
   }
 };
 
-// Test is flaky. crbug.com/723639
-PREF_HASH_BROWSER_TEST(PrefHashBrowserTestUnchangedDefault,
-                       DISABLED_UnchangedDefault);
+PREF_HASH_BROWSER_TEST(PrefHashBrowserTestUnchangedDefault, UnchangedDefault);
 
 // Augments PrefHashBrowserTestUnchangedDefault to confirm that nothing is reset
 // when nothing is tampered with, even if Chrome itself wrote custom prefs in
@@ -548,9 +561,7 @@ class PrefHashBrowserTestUnchangedCustom
   }
 };
 
-// Test is flaky. crbug.com/723639
-PREF_HASH_BROWSER_TEST(PrefHashBrowserTestUnchangedCustom,
-                       DISABLED_UnchangedCustom);
+PREF_HASH_BROWSER_TEST(PrefHashBrowserTestUnchangedCustom, UnchangedCustom);
 
 // Verifies that cleared prefs are reported.
 class PrefHashBrowserTestClearedAtomic : public PrefHashBrowserTestBase {
@@ -622,9 +633,7 @@ class PrefHashBrowserTestClearedAtomic : public PrefHashBrowserTestBase {
   }
 };
 
-// Test is flaky. crbug.com/723639
-PREF_HASH_BROWSER_TEST(PrefHashBrowserTestClearedAtomic,
-                       DISABLED_ClearedAtomic);
+PREF_HASH_BROWSER_TEST(PrefHashBrowserTestClearedAtomic, ClearedAtomic);
 
 // Verifies that clearing the MACs results in untrusted Initialized pings for
 // non-null protected prefs.
@@ -758,9 +767,8 @@ class PrefHashBrowserTestUntrustedInitialized : public PrefHashBrowserTestBase {
   }
 };
 
-// Test is flaky. crbug.com/723639
 PREF_HASH_BROWSER_TEST(PrefHashBrowserTestUntrustedInitialized,
-                       DISABLED_UntrustedInitialized);
+                       UntrustedInitialized);
 
 // Verifies that changing an atomic pref results in it being reported (and reset
 // if the protection level allows it).
@@ -858,9 +866,7 @@ class PrefHashBrowserTestChangedAtomic : public PrefHashBrowserTestBase {
   }
 };
 
-// Test is flaky. crbug.com/723639
-PREF_HASH_BROWSER_TEST(PrefHashBrowserTestChangedAtomic,
-                       DISABLED_ChangedAtomic);
+PREF_HASH_BROWSER_TEST(PrefHashBrowserTestChangedAtomic, ChangedAtomic);
 
 // Verifies that changing or adding an entry in a split pref results in both
 // items being reported (and remove if the protection level allows it).
@@ -967,9 +973,7 @@ class PrefHashBrowserTestChangedSplitPref : public PrefHashBrowserTestBase {
   }
 };
 
-// Test is flaky. crbug.com/723639
-PREF_HASH_BROWSER_TEST(PrefHashBrowserTestChangedSplitPref,
-                       DISABLED_ChangedSplitPref);
+PREF_HASH_BROWSER_TEST(PrefHashBrowserTestChangedSplitPref, ChangedSplitPref);
 
 // Verifies that adding a value to unprotected preferences for a key which is
 // still using the default (i.e. has no value stored in protected preferences)
@@ -1053,9 +1057,8 @@ class PrefHashBrowserTestUntrustedAdditionToPrefs
   }
 };
 
-// Test is flaky. crbug.com/723639
 PREF_HASH_BROWSER_TEST(PrefHashBrowserTestUntrustedAdditionToPrefs,
-                       DISABLED_UntrustedAdditionToPrefs);
+                       UntrustedAdditionToPrefs);
 
 // Verifies that adding a value to unprotected preferences while wiping a
 // user-selected value from protected preferences doesn't allow that value to
@@ -1141,9 +1144,8 @@ class PrefHashBrowserTestUntrustedAdditionToPrefsAfterWipe
   }
 };
 
-// Test is flaky. crbug.com/723639
 PREF_HASH_BROWSER_TEST(PrefHashBrowserTestUntrustedAdditionToPrefsAfterWipe,
-                       DISABLED_UntrustedAdditionToPrefsAfterWipe);
+                       UntrustedAdditionToPrefsAfterWipe);
 
 #if defined(OS_WIN)
 class PrefHashBrowserTestRegistryValidationFailure
@@ -1186,9 +1188,8 @@ class PrefHashBrowserTestRegistryValidationFailure
   }
 };
 
-// Test is flaky. crbug.com/723639
 PREF_HASH_BROWSER_TEST(PrefHashBrowserTestRegistryValidationFailure,
-                       DISABLED_RegistryValidationFailure);
+                       RegistryValidationFailure);
 #endif
 
 // Verifies that all preferences related to choice of default search engine are
@@ -1293,6 +1294,4 @@ class PrefHashBrowserTestDefaultSearch : public PrefHashBrowserTestBase {
   }
 };
 
-// Test is flaky. crbug.com/723639
-PREF_HASH_BROWSER_TEST(PrefHashBrowserTestDefaultSearch,
-                       DISABLED_SearchProtected);
+PREF_HASH_BROWSER_TEST(PrefHashBrowserTestDefaultSearch, SearchProtected);