Remove the mac_views_browser gn variable.

It's now redundant with is_mac.

The biggest use of it was that it set the buildflag MAC_VIEWS_BROWSER,
but I removed all references to that in the last few days:
https://cs.chromium.org/chromium/src/ui/base/BUILD.gn?q=%5CbMAC_VIEWS_BROWSER+case:yes

Bug: 832676
Change-Id: I9bd74e26a35ddb4dfec786e4b0a6ada24366c951
Reviewed-on: https://chromium-review.googlesource.com/c/1258295Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596238}

chrome/app/theme/theme_resources.grd

@@ -305,11 +305,9 @@
       <if expr="is_macosx">
         <structure type="chrome_scaled_image" name="IDR_THEME_TAB_BACKGROUND" file="mac/theme_default_inactive.png" />
         <structure type="chrome_scaled_image" name="IDR_THEME_TAB_BACKGROUND_INACTIVE" file="mac/theme_default_inactive_background.png" />
-        <if expr="mac_views_browser">
         <structure type="chrome_scaled_image" name="IDR_THEME_TAB_BACKGROUND_INCOGNITO" file="mac/theme_default_inactive.png" />
         <structure type="chrome_scaled_image" name="IDR_THEME_TAB_BACKGROUND_INCOGNITO_INACTIVE" file="mac/theme_default_inactive_background.png" />
       </if>
-      </if>
       <if expr="not is_macosx">
         <structure type="chrome_scaled_image" name="IDR_THEME_TAB_BACKGROUND" file="notused.png" />
         <structure type="chrome_scaled_image" name="IDR_THEME_TAB_BACKGROUND_INACTIVE" file="notused.png" />

chrome/browser/ui/views/browser_dialogs_views.cc

@@ -16,11 +16,7 @@
 #include "chrome/browser/ui/views_mode_controller.h"
 
 // This file provides definitions of desktop browser dialog-creation methods for
-// all toolkit-views platforms other than Mac. It also provides the definitions
-// on Mac when mac_views_browser=1 is specified in GYP_DEFINES. The file is
-// excluded in a Mac Cocoa build: definitions under chrome/browser/ui/cocoa may
-// select at runtime whether to show a Cocoa dialog, or the toolkit-views dialog
-// provided by browser_dialogs.h.
+// all toolkit-views platforms.
 // static
 scoped_refptr<LoginHandler> LoginHandler::Create(
     net::AuthChallengeInfo* auth_info,

chrome/common/features.gni

@@ -85,7 +85,6 @@ chrome_grit_defines = [
   "enable_printing=$enable_basic_printing",
   "enable_service_discovery=$enable_service_discovery",
   "enable_vr=$enable_vr",
-  "mac_views_browser=$mac_views_browser",
   "safe_browsing_mode=$safe_browsing_mode",
   "optimize_webui=$optimize_webui",
 ]

ui/base/BUILD.gn

@@ -58,7 +58,6 @@ buildflag_header("ui_features") {
     "ENABLE_MUS=$enable_mus",
     "USE_ATK=$use_atk",
     "USE_XKBCOMMON=$use_xkbcommon",
-    "MAC_VIEWS_BROWSER=$mac_views_browser",
     "HAS_NATIVE_ACCESSIBILITY=$has_native_accessibility",
   ]
 }

ui/base/ui_features.gni

@@ -19,8 +19,3 @@ declare_args() {
 }
 
 enable_hidpi = is_mac || is_win || is_linux
-
-# Whether the entire browser uses toolkit-views on Mac instead of Cocoa.
-# TODO(https://crbug.com/832676): Now that this is always true, remove all uses
-# of this and then remove it.
-mac_views_browser = is_mac