Revert of Revert of linux/gyp: Find missing symbols at build time, not runtime.

content/content_browser.gypi

Index: content/content_browser.gypi
diff --git a/content/content_browser.gypi b/content/content_browser.gypi
index 7d77bd38481185eaf9d3b4dfc4094949851062f9..f5fa1f80c187da456f4d21b5f9dbb83eddb07dd1 100644
--- a/content/content_browser.gypi
+++ b/content/content_browser.gypi
@@ -1813,6 +1813,8 @@
     ['use_x11==1', {
       'dependencies': [
         '../build/linux/system.gyp:x11',
+        '../ui/events/platform/x11/x11_events_platform.gyp:x11_events_platform',
+        '../ui/gfx/x/gfx_x11.gyp:gfx_x11',
       ],
     }],
     ['use_pango==1', {