Reland: Enable touch text selection by default on desktop Aura

--disable-touch-editing can be used to disable touch text selection.

Originally landed as r274972, but reverted due to blink layout test
failures. Layout tests are fixed in r175595 (blink).

BUG=304872

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=274972

Review URL: https://codereview.chromium.org/305423003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@275452 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/about_flags.cc

@@ -1155,7 +1155,7 @@ const Experiment kExperiments[] = {
     "enable-touch-editing",
     IDS_FLAGS_ENABLE_TOUCH_EDITING_NAME,
     IDS_FLAGS_ENABLE_TOUCH_EDITING_DESCRIPTION,
-    kOsCrOS,
+    kOsCrOS | kOsWin | kOsLinux,
     ENABLE_DISABLE_VALUE_TYPE(switches::kEnableTouchEditing,
                               switches::kDisableTouchEditing)
   },

ui/base/ui_base_switches_util.cc

@@ -25,7 +25,7 @@ bool IsTouchDragDropEnabled() {
 }
 
 bool IsTouchEditingEnabled() {
-#if defined(OS_CHROMEOS)
+#if defined(USE_AURA)
   return !CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kDisableTouchEditing);
 #else