gn BUILD fixes for disabling enable_extensions and use_ash feature flags.

chrome/browser/media/router/BUILD.gn

Index: chrome/browser/media/router/BUILD.gn
diff --git a/chrome/browser/media/router/BUILD.gn b/chrome/browser/media/router/BUILD.gn
index 8e14962577f5426491f211829e3e81540866154d..3c42873c1070fa54206515da8909d8ca62f41a3d 100644
--- a/chrome/browser/media/router/BUILD.gn
+++ b/chrome/browser/media/router/BUILD.gn
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 #
 
+import("//build/config/features.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 
@@ -26,9 +27,11 @@ static_library("router") {
   if (!is_android) {
     deps += [
       ":mojo_bindings",
-      "//extensions/browser",
       "//mojo/public/cpp/bindings",
     ]
+    if (enable_extensions) {

[mark a. foltz, 2016/05/19 20:00:39]

Is there now a valid build target with !is_android and !enable_extensions? 
media_router_non_android_sources won't compile without these deps.

[asaka, 2016/05/20 05:59:41]

Hi!

I think chromecast may end up as that with this patch? The linux build worked
for me on my local build from your repository. (gn gen out/Debug
--args='is_chromecast=true is_debug=true'; ninja -C out/Debug cast_shell) 

What do you think?

[mark a. foltz, 2016/05/20 17:48:21]

I think this works because //chromecast is prevented from depending on //chrome,
so cast_shell doesn't depend on this target anyway.  (You can double check with
gn.)

The right fix would probably be to add more conditions to enable_media_router to
exclude is_chromecast, and ensure that enable_extensions is set on the
appropriate platforms.  We can make that fix in a separate patch.

As is, this change doesn't make a lot of sense in isolation.  For example try
building chrome or unit_tests with is_android=false enable_extensions=false.  I
recommend reverting this file.

[asaka, 2016/05/24 10:57:31]

Reverting this change only will not build:

$ gn gen out/Debug --args='is_chromecast=true is_debug=true'
ERROR at //extensions/strings/BUILD.gn:7:1: Assertion failed.
assert(enable_extensions)
^-----
See //extensions/browser/BUILD.gn:29:5: which caused the file to be included.
    "//extensions/strings",
    ^---------------------

gn gen out/Debug --args='is_chromecast=true is_debug=true
enable_media_router=false' seems to work. I can build it and "something" starts
up on linux.

For generic build I also need to do --args="enable_extensions=false
enable_media_router=false" since --args="enable_extensions=false" 'gn gen' will
fail. I think making this dependency sounds suboptimal, but since this file is
not the main conflict in out imports I can accept it in this patch from our pov.


is_andorid is not a valid argument for out/Default afaict. But I assume that
when I do a general chrome build with just "--enable_extensions=false" I will
also get is_android = false since I runt the binary on my linux host after? I
verified this works with this patch earlier.

+      deps += [ "//extensions/browser" ]
+    }
     sources += rebase_path(gypi_values.media_router_non_android_sources,
                            ".",
                            "//chrome/browser/media/router")
@@ -52,10 +55,10 @@ source_set("test_support") {
                         ".",
                         "//chrome/browser/media/router")
   if (!is_android) {
-    deps += [
-      ":mojo_bindings",
-      "//extensions/common",
-    ]
+    deps += [ ":mojo_bindings" ]
+    if (enable_extensions) {
+      deps += [ "//extensions/common" ]
+    }
     sources +=
         rebase_path(gypi_values.media_router_non_android_test_support_sources,
                     ".",