Forward Port M67 Disable Touchable UI by Default Except on Tablets

BUG=842291,875122
TBR=kylixrd@chromium.org,sky@chromium.org

Change-Id: Ieef37d1c681f109c41ef2451ed68f341b59531b1
Reviewed-on: https://chromium-review.googlesource.com/1066803
Cr-Original-Commit-Position: refs/branch-heads/3396@{#660}
Cr-Original-Branched-From: 9ef2aa86-refs/heads/master@{#550428}(cherry picked from commit 76c3965de85bcd28a57293cef653a88cbb6061af)
Reviewed-on: https://chromium-review.googlesource.com/1179341Reviewed-by: Robert Liao <robliao@chromium.org>
Commit-Queue: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583952}

ui/base/material_design/material_design_controller.cc

@@ -54,10 +54,10 @@ bool IsMaterialRefreshEnabled() {
 
 #if defined(OS_CHROMEOS)
 
-// Whether to use MATERIAL_TOUCH_OPTIMIZED when a touch device is detected.
-// Enabled by default on ChromeOS.
+// Whether to use touchable UI.
+// http://crbug.com/875122 - Disabled by default on ChromeOS except on tablets.
 const base::Feature kTouchOptimizedUi = {"TouchOptimizedUi",
-                                         base::FEATURE_ENABLED_BY_DEFAULT};
+                                         base::FEATURE_DISABLED_BY_DEFAULT};
 
 MaterialDesignController::Mode GetDefaultTouchDeviceMode() {
   bool material_refresh_enabled = IsMaterialRefreshEnabled();