Postpone the content duplication check until starting import.

ui/file_manager/file_manager/foreground/js/import_controller.js

Index: ui/file_manager/file_manager/foreground/js/import_controller.js
diff --git a/ui/file_manager/file_manager/foreground/js/import_controller.js b/ui/file_manager/file_manager/foreground/js/import_controller.js
index 8659572986716a7f1d0d382d9121425fb6f19738..a2963c81d8c1e7542db2746aeba33ded5ba77cfc 100644
--- a/ui/file_manager/file_manager/foreground/js/import_controller.js
+++ b/ui/file_manager/file_manager/foreground/js/import_controller.js
@@ -175,7 +175,7 @@ importer.ImportController.prototype.onDirectoryChanged_ = function(event) {
   this.scanManager_.reset();
   if (this.isCurrentDirectoryScannable_()) {
     this.checkState_(
-        this.scanManager_.getDirectoryScan(importer.ScanMode.CONTENT));
+        this.scanManager_.getDirectoryScan(importer.ScanMode.HISTORY));
   } else {
     this.checkState_();
   }
@@ -202,7 +202,7 @@ importer.ImportController.prototype.onSelectionChanged_ = function() {
   if (this.environment_.getSelection().length === 0 &&
       this.isCurrentDirectoryScannable_()) {
     this.checkState_(
-        this.scanManager_.getDirectoryScan(importer.ScanMode.CONTENT));
+        this.scanManager_.getDirectoryScan(importer.ScanMode.HISTORY));
   } else {
     this.checkState_();
   }
@@ -226,7 +226,7 @@ importer.ImportController.prototype.onScanInvalidated_ = function() {
   if (this.environment_.getSelection().length === 0 &&
       this.isCurrentDirectoryScannable_()) {
     this.checkState_(
-        this.scanManager_.getDirectoryScan(importer.ScanMode.CONTENT));
+        this.scanManager_.getDirectoryScan(importer.ScanMode.HISTORY));
   } else {
     this.checkState_();
   }
@@ -367,7 +367,7 @@ importer.ImportController.prototype.checkState_ = function(opt_scan) {
     // NOTE, that tryScan_ lazily initializes scans...so if
     // no scan is returned, no scan is possible for the
     // current context.
-    var scan = this.tryScan_(importer.ScanMode.CONTENT);
+    var scan = this.tryScan_(importer.ScanMode.HISTORY);
     // If no scan is created, then no scan is possible in
     // the current context...so hide the UI.
     if (!scan) {