[chrome.displaySource] Implement software based H.264 video encoder.

extensions/renderer/BUILD.gn

Index: extensions/renderer/BUILD.gn
diff --git a/extensions/renderer/BUILD.gn b/extensions/renderer/BUILD.gn
index 1b8f7d0efbe3a9fcfe5666193b1d1c2249e3aef6..0c3f8ecce7aea1348ed4ca2f22a93816f2127c1f 100644
--- a/extensions/renderer/BUILD.gn
+++ b/extensions/renderer/BUILD.gn
@@ -32,13 +32,16 @@ source_set("renderer") {
     "//third_party/WebKit/public:blink",
   ]
 
-  if (enable_wifi_display) {
+  if (proprietary_codecs && enable_wifi_display) {
     wifi_display_sources = rebase_path(
             extensions_gypi_values.extensions_renderer_sources_wifi_display,
             ".",
             "//extensions")
     sources += wifi_display_sources
 
-    deps += [ "//third_party/wds:libwds" ]
+    deps += [
+      "//third_party/openh264/openh264.gyp:openh264_encoder",
+      "//third_party/wds:libwds",
+    ]
   }
 }