Use TaskScheduler instead of blocking pool in enumerate_modules_model.cc.

chrome/browser/win/enumerate_modules_model.h

Index: chrome/browser/win/enumerate_modules_model.h
diff --git a/chrome/browser/win/enumerate_modules_model.h b/chrome/browser/win/enumerate_modules_model.h
index 76ce0227904495040d4d729af10fdd2417c4a148..d2bc5785bbee3850843e558b55894bf7cd6f865d 100644
--- a/chrome/browser/win/enumerate_modules_model.h
+++ b/chrome/browser/win/enumerate_modules_model.h
@@ -141,18 +141,11 @@ class ModuleEnumerator {
  private:
   FRIEND_TEST_ALL_PREFIXES(EnumerateModulesTest, CollapsePath);
 
-  // This function enumerates all modules in the blocking pool. Once the list of
-  // module filenames is populated it posts a delayed task to call
-  // ScanImplDelay for the first module.
+  // This function posts a task to enumerate all modules asynchronously. Once
+  // the list of module filenames is populated, a delayed task is posted to scan
+  // the first module.
   void ScanImplStart();
 
-  // Immediately posts a CONTINUE_ON_SHUTDOWN task to ScanImplModule for the
-  // given module. This ping-ponging is because the blocking pool does not
-  // offer a delayed CONTINUE_ON_SHUTDOWN task.
-  // TODO(chrisha): When the new scheduler enables delayed CONTINUE_ON_SHUTDOWN
-  // tasks, simplify this logic.
-  void ScanImplDelay(size_t index);
-
   // Inspects the module in |enumerated_modules_| at the given |index|. Gets
   // module information, normalizes it, and collapses the path. This is an
   // expensive operation and non-critical. Posts a delayed task to ScanImplDelay
@@ -210,6 +203,9 @@ class ModuleEnumerator {
   // The typedef for the vector that maps a regular file path to %env_var%.
   typedef std::vector<std::pair<base::string16, base::string16>> PathMapping;
 
+  // The TaskRunner to perform work in the background.
+  const scoped_refptr<base::TaskRunner> background_task_runner_;
+
   // The vector of paths to %env_var%, used to account for differences in
   // where people keep there files, c:\windows vs. d:\windows, etc.
   PathMapping path_mapping_;
@@ -248,7 +244,7 @@ class ModuleEnumerator {
 // ready.
 //
 // The member functions of this class may only be used from the UI thread. The
-// bulk of the work is actually performed in the blocking pool with
+// bulk of the work is actually performed asynchronously in TaskScheduler with
 // CONTINUE_ON_SHUTDOWN semantics, as the WinCrypt functions can effectively
 // block arbitrarily during shutdown.
 //
@@ -341,13 +337,13 @@ class EnumerateModulesModel {
   void DoneScanning();
 
   // The vector containing all the modules enumerated. Will be normalized and
-  // any bad modules will be marked. Written to from the blocking pool by the
-  // |module_enumerator_|, read from on the UI thread by this class.
+  // any bad modules will be marked. Written to from the background TaskRunner
+  // by
+  // the |module_enumerator_|, read from on the UI thread by this class.

[Finnur, 2017/02/21 10:45:55]

nit: These two lines can be consolidated.

[fdoray, 2017/02/22 18:53:06]

Done.

   ModuleEnumerator::ModulesVector enumerated_modules_;
 
-  // The object responsible for enumerating the modules in the blocking pool.
-  // Only used from the UI thread. This ends up internally doing its work in the
-  // blocking pool.
+  // The object responsible for enumerating the modules on a background
+  // TaskRunner. Only accessed from the UI thread.
   std::unique_ptr<ModuleEnumerator> module_enumerator_;
 
   // Whether the conflict notification has been acknowledged by the user. Only