"Tablet" instead of "TouchView" in "Force Ui Mode" flag.

Bug: None
Change-Id: I97e0cccfc77d51bbf738bfab307b8b98d34040be
Reviewed-on: https://chromium-review.googlesource.com/c/1318797Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605564}

chrome/browser/flag_descriptions.cc

@@ -3540,7 +3540,7 @@ const char kUiModeDescription[] =
     R"*(means that the chromebook will act as if it were in clamshell )*"
     R"*(mode . "Auto" means that the chromebook will alternate between )*"
     R"*(the two, based on its orientation.)*";
-const char kUiModeTablet[] = "TouchView";
+const char kUiModeTablet[] = "Tablet";
 const char kUiModeClamshell[] = "Clamshell";
 const char kUiModeAuto[] = "Auto (default)";