[Sync] Refactoring of sync integration test checkers to remove boilerplate await methods.

chrome/browser/sync/test/integration/themes_helper.h

Index: chrome/browser/sync/test/integration/themes_helper.h
diff --git a/chrome/browser/sync/test/integration/themes_helper.h b/chrome/browser/sync/test/integration/themes_helper.h
index dce9cbbb1ca7e18fe5753ee095983466693002e6..feee0e041744ef7968be325ad422b2999ee1bdda 100644
--- a/chrome/browser/sync/test/integration/themes_helper.h
+++ b/chrome/browser/sync/test/integration/themes_helper.h
@@ -7,10 +7,15 @@
 
 #include <string>
 
+#include "base/callback.h"
 #include "base/compiler_specific.h"
+#include "chrome/browser/sync/test/integration/status_change_checker.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 
 class Profile;
+class ThemeService;
 
 namespace themes_helper {
 
@@ -43,18 +48,82 @@ void UseDefaultTheme(Profile* profile);
 // Sets |profile| to use the system theme.
 void UseSystemTheme(Profile* profile);
 
-// Waits until |theme| is pending for install on |profile|.
-// Returns false in case of timeout.
-bool AwaitThemeIsPendingInstall(Profile* profile, const std::string& theme);
+}  // namespace themes_helper
 
 // Waits until |profile| is using the system theme.
 // Returns false in case of timeout.
-bool AwaitUsingSystemTheme(Profile* profile);
 
 // Waits until |profile| is using the default theme.
 // Returns false in case of timeout.
-bool AwaitUsingDefaultTheme(Profile* profile);
 
-}  // namespace themes_helper
+// Helper to wait until a given condition is met, checking every time the
+// current theme changes.
+//
+// The |exit_condition_| closure may be invoked zero or more times.
+class ThemeConditionChecker : public StatusChangeChecker,
+                              public content::NotificationObserver {
+ public:
+  ThemeConditionChecker(Profile* profile,
+                        const std::string& debug_message_,
+                        base::Callback<bool(ThemeService*)> exit_condition);
+  ~ThemeConditionChecker() override;
+
+  // Implementation of StatusChangeChecker.
+  std::string GetDebugMessage() const override;
+  bool IsExitConditionSatisfied() override;
+
+  // Implementation of content::NotificationObserver.
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
+
+ private:
+  Profile* profile_;
+  const std::string debug_message_;
+  base::Callback<bool(ThemeService*)> exit_condition_;
+
+  content::NotificationRegistrar registrar_;
+};
+
+// Waits until |theme| is pending for install on |profile|.
+// Returns false in case of timeout.
+
+// Helper to wait until the specified theme is pending for install on the
+// specified profile.
+//
+// The themes sync integration tests don't actually install any custom themes,
+// but they do occasionally check that the ThemeService attempts to install
+// synced themes.
+class ThemePendingInstallChecker : public StatusChangeChecker,
+                                   public content::NotificationObserver {
+ public:
+  ThemePendingInstallChecker(Profile* profile, const std::string& theme);
+  ~ThemePendingInstallChecker() override;
+
+  // Implementation of StatusChangeChecker.
+  std::string GetDebugMessage() const override;
+  bool IsExitConditionSatisfied() override;
+
+  // Implementation of content::NotificationObserver.
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
+
+ private:
+  Profile* profile_;
+  const std::string& theme_;
+
+  content::NotificationRegistrar registrar_;
+};
+
+class SystemThemeChecker : public ThemeConditionChecker {
+ public:
+  explicit SystemThemeChecker(Profile* profile);
+};
+
+class DefaultThemeChecker : public ThemeConditionChecker {
+ public:
+  explicit DefaultThemeChecker(Profile* profile);
+};
 
 #endif  // CHROME_BROWSER_SYNC_TEST_INTEGRATION_THEMES_HELPER_H_