Content Settings: Add RevocationObserver to measure when permissions are revoked

chrome/browser/permissions/permission_util_unittest.cc

+// Copyright 2016 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 "chrome/browser/content_settings/host_content_settings_map_factory.h"
+#include "chrome/browser/permissions/permission_util.h"
+#include "chrome/test/base/testing_profile.h"
+#include "components/content_settings/core/browser/host_content_settings_map.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+class PermissionUtilTest : public testing::Test {
+  content::TestBrowserThreadBundle thread_bundle_;
+};
+
+TEST_F(PermissionUtilTest, SetContentSettingRecordRevocation) {
+  TestingProfile profile;
+  HostContentSettingsMap* map =
+      HostContentSettingsMapFactory::GetForProfile(&profile);
+  GURL host("https://example.com");
+  ContentSettingsType type = CONTENT_SETTINGS_TYPE_GEOLOCATION;
+
+  // Allow->Block triggers a revocation.
+  map->SetContentSettingDefaultScope(host, host, type, "",

[Bernhard Bauer, 2016/03/22 10:13:30]

Nit: Use an empty std::string() constructor instead of a literal to save a
couple of instructions. Less important in a test, but tests are often used as
examples of usage, so I'd like to behave there ☺

[tsergeant, 2016/03/22 23:55:20]

Done.

+                                     CONTENT_SETTING_ALLOW);
+  EXPECT_TRUE(PermissionUtil::SetContentSettingRecordRevocation(

[Bernhard Bauer, 2016/03/22 10:13:29]

If the return value is only used for tests, it might be better to verify that
this method actually records the metric and doesn't just claim it did ☺ I think
you should be able to use base::HistogramTester to verify what gets recorded.

[tsergeant, 2016/03/22 23:55:20]

Done. I don't want to get too deep into testing the implementation of
PermissionUmaUtil, I've made a TODO for doing that separately.

+      &profile, host, host, type, "", CONTENT_SETTING_BLOCK));
+
+  // Block->Allow does not trigger a revocation.
+  EXPECT_FALSE(PermissionUtil::SetContentSettingRecordRevocation(
+      &profile, host, host, type, "", CONTENT_SETTING_ALLOW));
+
+  // Allow->Default triggers a revocation when default is 'ask'.
+  map->SetDefaultContentSetting(type, CONTENT_SETTING_ASK);
+  EXPECT_TRUE(PermissionUtil::SetContentSettingRecordRevocation(
+      &profile, host, host, type, "", CONTENT_SETTING_DEFAULT));
+
+  // Allow->Default does not trigger a revocation when default is 'allow'.
+  map->SetDefaultContentSetting(type, CONTENT_SETTING_ALLOW);
+  EXPECT_FALSE(PermissionUtil::SetContentSettingRecordRevocation(
+      &profile, host, host, type, "", CONTENT_SETTING_DEFAULT));
+}