Enable opening context menu by two-finger tap.

The context menu has once disabled by 606068 when we assigned long-tap
to enter the selection mode.

Bug: 755757
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I282901d190e63c264eb6238abd34bf0cff107a66
Reviewed-on: https://chromium-review.googlesource.com/625506Reviewed-by: Naoki Fukino <fukino@chromium.org>
Commit-Queue: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#496599}

ui/file_manager/file_manager/foreground/js/ui/file_tap_handler.js

@@ -108,13 +108,17 @@ FileTapHandler.prototype.handleTouchEvents = function(event, index, callback) {
     case 'touchstart':
       // Only process single touches.  If there is already a touch happening, or
       // two simultaneous touches then just ignore them.
-      if (event.touches.length > 1)
+      if (event.touches.length > 1) {
         // Note that we could cancel an active touch here.  That would make
         // simultaneous touch behave similar to near-simultaneous. However, if
         // the user is dragging something, an accidental second touch could be
         // quite disruptive if it cancelled their drag.  Better to just ignore
         // it.
+
+        // Invalidate current touch to distinguish it from normal tap.
+        this.tapStarted_ = false;
         return false;
+      }
 
       // It's still possible there could be an active "touch" if the user is
       // simultaneously using a mouse and a touch input.
@@ -142,8 +146,6 @@ FileTapHandler.prototype.handleTouchEvents = function(event, index, callback) {
       break;
 
     case 'touchmove':
-      assert(this.findActiveTouch_(event.touches), 'Missing touchEnd');
-
       var touch = this.findActiveTouch_(event.changedTouches);
       if (!touch)
         break;

ui/file_manager/file_manager/foreground/js/ui/list_container.js

@@ -105,6 +105,13 @@ function ListContainer(element, table, grid) {
    */
   this.textSearchState = new TextSearchState();
 
+  /**
+   * Whtehter to allow or cancel a context menu event.
+   * @type {boolean}
+   * @private
+   */
+  this.allowContextMenuByTouch_ = false;
+
   // Overriding the default role 'list' to 'listbox' for better accessibility
   // on ChromeOS.
   this.table.list.setAttribute('role', 'listbox');
@@ -118,12 +125,7 @@ function ListContainer(element, table, grid) {
   util.isTouchModeEnabled().then(function(enabled) {
     if (!enabled)
       return;
-    // Prevent opening context menu in file list by tap.
-    this.element.addEventListener('contextmenu', function(e) {
-      if (e.sourceCapabilities && e.sourceCapabilities.firesTouchEvents) {
-        e.stopPropagation();
-      }
-    }, true);
+    this.disableContextMenuByLongTap_();
   }.bind(this));
 }
 
@@ -241,6 +243,34 @@ ListContainer.prototype.setCurrentListType = function(listType) {
   this.endBatchUpdates();
 };
 
+/**
+ * Disables context menu by long-tap but not two-finger tap.
+ * @private
+ */
+ListContainer.prototype.disableContextMenuByLongTap_ = function() {
+  this.element.addEventListener('touchstart', function(e) {
+    if (e.touches.length > 1) {
+      this.allowContextMenuByTouch_ = true;
+    }
+  }.bind(this));
+  this.element.addEventListener('touchend', function(e) {
+    if (e.touches.length == 0) {
+      // contextmenu event will be sent right after touchend.
+      setTimeout(function() {
+        this.allowContextMenuByTouch_ = false;
+      }.bind(this));
+    }
+  }.bind(this));
+  this.element.addEventListener('contextmenu', function(e) {
+    // Block context menu triggered by touch event unless it is right after
+    // multi-touch.
+    if (!this.allowContextMenuByTouch_ && e.sourceCapabilities &&
+        e.sourceCapabilities.firesTouchEvents) {
+      e.stopPropagation();
+    }
+  }.bind(this), true);
+};
+
 /**
  * Clears hover highlighting in the list container until next mouse move.
  */