Don't compile code for desktop zoom or GuestViews on mobile platforms.

chrome/browser/ui/BUILD.gn

Index: chrome/browser/ui/BUILD.gn
diff --git a/chrome/browser/ui/BUILD.gn b/chrome/browser/ui/BUILD.gn
index e6c344596e8f74424e743955aa22f67b794bb3e1..f54ce05302d954754a4c8d7515b0433af5a2c819 100644
--- a/chrome/browser/ui/BUILD.gn
+++ b/chrome/browser/ui/BUILD.gn
@@ -442,10 +442,6 @@ split_static_library("ui") {
     "webui/version_ui.cc",
     "webui/version_ui.h",
     "window_sizer/window_sizer_mac.mm",
-    "zoom/chrome_zoom_level_otr_delegate.cc",
-    "zoom/chrome_zoom_level_otr_delegate.h",
-    "zoom/chrome_zoom_level_prefs.cc",
-    "zoom/chrome_zoom_level_prefs.h",
   ]
 
   defines = []
@@ -516,7 +512,6 @@ split_static_library("ui") {
     "//components/flags_ui",
     "//components/gcm_driver",
     "//components/google/core/browser",
-    "//components/guest_view/browser",
     "//components/history/content/browser",
     "//components/image_fetcher/core",
     "//components/infobars/core",
@@ -581,7 +576,6 @@ split_static_library("ui") {
     "//components/version_ui",
     "//components/web_cache/browser",
     "//components/web_resource",
-    "//components/zoom",
     "//content/app/resources",
     "//content/public/common",
     "//crypto",
@@ -636,6 +630,7 @@ split_static_library("ui") {
   if (enable_extensions) {
     deps += [
       "//components/drive",
+      "//components/guest_view/browser",

[msw, 2017/05/12 18:06:32]

Does this belong here? I have no idea what a "guest view" is, or if its related
to extensions, and the class comments in that directory aren't terribly
enlightening. I see that you answered Avi's similar question, but please ask one
of their owners for review of this change, and maybe they'll be inclined to
improve their component name/docs.

[Kevin McNee, 2017/05/15 18:22:18]

I've talked with wjmaclean and lfg offline about this and I've created a bug to
add an explicit build flag for GuestViews instead of relying on extensions (
crbug.com/722453 ). Other GuestView callers are #ifdef'd behind
ENABLE_EXTENSIONS and sometimes !OS_ANDROID, and nothing outside of extensions
currently uses GuestViews, so for now, using enable_extensions here is
reasonable.

       "//extensions/browser",
       "//extensions/strings",
     ]
@@ -1189,6 +1184,10 @@ split_static_library("ui") {
       "webui/uber/uber_ui.h",
       "window_sizer/window_sizer.cc",
       "window_sizer/window_sizer.h",
+      "zoom/chrome_zoom_level_otr_delegate.cc",
+      "zoom/chrome_zoom_level_otr_delegate.h",
+      "zoom/chrome_zoom_level_prefs.cc",
+      "zoom/chrome_zoom_level_prefs.h",
     ]
     deps += [
       "//apps",
@@ -1199,6 +1198,7 @@ split_static_library("ui") {
       "//components/feedback/proto",
       "//components/proximity_auth/webui",
       "//components/web_modal",
+      "//components/zoom",
       "//device/bluetooth",
       "//extensions/common:mojo",
       "//mash/public/interfaces",
@@ -3542,7 +3542,6 @@ static_library("test_support") {
     "//components/sessions",
     "//components/toolbar",
     "//components/translate/content/browser",
-    "//components/zoom",
     "//content/public/browser",
     "//content/public/common",
     "//content/test:test_support",
@@ -3591,7 +3590,10 @@ static_library("test_support") {
       "test/test_confirm_bubble_model.cc",
       "test/test_confirm_bubble_model.h",
     ]
-    deps += [ "//chrome/test:test_support_ui" ]
+    deps += [
+      "//chrome/test:test_support_ui",
+      "//components/zoom",
+    ]
   }
 
   if (enable_extensions) {