Reland of Setting is_component_build to false by default

webrtc/webrtc.gni

Index: webrtc/webrtc.gni
diff --git a/webrtc/webrtc.gni b/webrtc/webrtc.gni
index 96975fae9a4227568632a0fc50932d487cd134ac..6f902c97bf393c9b27673fc425d2b0bfa5663c63 100644
--- a/webrtc/webrtc.gni
+++ b/webrtc/webrtc.gni
@@ -13,6 +13,21 @@ import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/ui.gni")
 import("//build_overrides/build.gni")
 import("//testing/test.gni")
+
+if (!build_with_chromium && is_component_build) {
+  print("The Gn argument `is_component_build` is currently " +
+        "ignored for WebRTC builds.")
+  print("Component builds are supported by Chromium and the argument " +
+        "`is_component_build` makes it possible to create shared libraries " +
+        "instead of static libraries.")
+  print("If an app depends on WebRTC it makes sense to just depend on the " +
+        "WebRTC static library, so there is no difference between " +
+        "`is_component_build=true` and `is_component_build=false`.")
+  print(
+      "More info about component builds at: " + "https://chromium.googlesource.com/chromium/src/+/master/docs/component_build.md")
+  assert(!is_component_build, "Component builds are not supported in WebRTC.")
+}
+
 if (is_ios) {
   import("//build/config/ios/rules.gni")
 }