Make chrome GN build work in component mode.

content/app/BUILD.gn

Index: content/app/BUILD.gn
diff --git a/content/app/BUILD.gn b/content/app/BUILD.gn
index f636d9f3735c42effbf1d52958ebc64f0d1de25e..d761c4fa172b6a5b47a03a7ef1d20606aaa48cd9 100644
--- a/content/app/BUILD.gn
+++ b/content/app/BUILD.gn
@@ -25,7 +25,7 @@ content_app_deps = [
   # picking the allocator.
   "//base/allocator",
   "//content:export",
-  "//content/public/common",
+  "//content/public/common:common_sources",
   "//crypto",
   "//ui/base",
   "//ui/gfx",
@@ -63,55 +63,41 @@ content_app_extra_configs = [
   "//content:content_implementation",
 ]
 
-if (is_component_build) {
-  source_set("app") {
-    sources = content_app_sources
-    configs += content_app_extra_configs
-    deps = content_app_deps
-  }
+# This includes the app sources for both the browser and child processes.
+source_set("both") {
+  # Only the public target should depend on this. All other targets (even
+  # internal content ones) should depend on the public one.
+  visibility = [ "//content/public/app:*" ]
 
-  # In the component build, all of these app targets redirect to the content
-  # component. The content component in turn references the "app" target above.
-  group("browser") {
-    deps = [ "//content" ]
-  }
-  group("child") {
-    deps = [ "//content" ]
-  }
-  group("both") {
-    deps = [ "//content" ]
-  }
-} else {
-  # Non-component build. In this case, we have different versions of
-  # "content/app" for the browser and child process.
+  sources = content_app_sources
+  configs += content_app_extra_configs
+  deps = content_app_deps
+}
 
-  # TODO(GYP) enable chrome_multiple_dll support
-  is_chrome_multiple_dll = false
+# TODO(GYP) enable chrome_multiple_dll support
+is_chrome_multiple_dll = false
+
+if (is_chrome_multiple_dll) {
+  # It doesn't make sense to do the browser/child dll split in component mode.
+  assert(!is_component_build)
 
   source_set("browser") {
+    visibility = [ "//content/public/app:browser" ]
+
     sources = content_app_sources
     configs += content_app_extra_configs
     deps = content_app_deps
 
-    if (is_chrome_multiple_dll) {
-      defines += [ "CHROME_MULTIPLE_DLL_BROWSER" ]
-    }
+    defines += [ "CHROME_MULTIPLE_DLL_BROWSER" ]
   }
 
   source_set("child") {
-    sources = content_app_sources
-    configs += content_app_extra_configs
-    deps = content_app_deps
-
-    if (is_chrome_multiple_dll) {
-      defines += [ "CHROME_MULTIPLE_DLL_CHILD" ]
-    }
-  }
+    visibility = [ "//content/public/app:child" ]
 
-  # Includes both browser and child process app sources.
-  source_set("both") {
     sources = content_app_sources
     configs += content_app_extra_configs
     deps = content_app_deps
+
+    defines += [ "CHROME_MULTIPLE_DLL_CHILD" ]
   }
 }