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

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

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_SYNC_TEST_INTEGRATION_STATUS_CHANGE_CHECKER_H_
 #define CHROME_BROWSER_SYNC_TEST_INTEGRATION_STATUS_CHANGE_CHECKER_H_
 
 #include <string>
 
 #include "base/time/time.h"
 
 class ProfileSyncServiceHarness;
 
 // Interface for a helper class that can pump the message loop while waiting
 // for a certain state transition to take place.
 //
 // This is a template that should be filled in by child classes so they can
 // observe specific kinds of changes and await specific conditions.
 //
 // The instances of this class are intended to be single-use.  It doesn't make
 // sense to call StartBlockingWait() more than once.
 class StatusChangeChecker {
  public:
-  explicit StatusChangeChecker();
+  StatusChangeChecker();
 
   // Returns a string representing this current StatusChangeChecker, and
   // possibly some small part of its state.  For example: "AwaitPassphraseError"
   // or "AwaitMigrationDone(BOOKMARKS)".
   virtual std::string GetDebugMessage() const = 0;
 
+  // Returns whether the state the checker is currently in is its desired
+  // configuration.
+  virtual bool IsExitConditionSatisfied() = 0;
+
+  // Block if IsExitConditionSatisfied() is currently false until TimedOut()
+  // becomes true. Checkers should call CheckExitCondition upon changes, which
+  // can cause Wait() to immediately return true if IsExitConditionSatisfied(),
+  // and continue to block if not. Returns true if and only if timeout occurs.

[maxbogue, 2016/09/30 19:03:53]

This is wrong now: "Returns true if and only if timeout occurs." should be
inverted.

[skym, 2016/09/30 19:06:52]

Done.

+  virtual bool Wait();
+
   // Returns true if the blocking wait was exited because of a timeout.
   bool TimedOut() const;
 
-  virtual bool IsExitConditionSatisfied() = 0;
-
  protected:
   virtual ~StatusChangeChecker();
 
   // Timeout length when blocking.
   virtual base::TimeDelta GetTimeoutDuration();
 
   // Helper function to start running the nested message loop.
   //
   // Will exit if IsExitConditionSatisfied() returns true when called from
   // CheckExitCondition(), if a timeout occurs, or if StopWaiting() is called.
   //
   // The timeout length is specified with GetTimeoutDuration().
   void StartBlockingWait();
 
   // Stop the nested running of the message loop started in StartBlockingWait().
   void StopWaiting();
 
   // Checks IsExitConditionSatisfied() and calls StopWaiting() if it returns
   // true.
   void CheckExitCondition();
 
   // Called when the blocking wait timeout is exceeded.
   void OnTimeout();
 
   bool timed_out_;
 };
 
 #endif  // CHROME_BROWSER_SYNC_TEST_INTEGRATION_STATUS_CHANGE_CHECKER_H_