Include bloat: reduce number of includes in content_browser_client.h

This reduces the number of preprocessor tokens in
content_browser_client.h from 1,335,281 to 754,474. Since this is a
widely included file, reducing build times a fair bit (see bug).

TBR=tsepez for content/browser/child_process_security_policy_*

Bug: 1014009
Change-Id: Id3c2de29f5b08cab80820d01aff722afeb1618e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1857126
Commit-Queue: Hans Wennborg <[email protected]>
Reviewed-by: Richard Coles <[email protected]>
Reviewed-by: Ken Rockot <[email protected]>
Reviewed-by: Nico Weber <[email protected]>
Reviewed-by: Camille Lamy <[email protected]>
Reviewed-by: Sami Kyöstilä <[email protected]>
Cr-Commit-Position: refs/heads/master@{#706388}
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 1d12fe4dd..b92e423 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -127,6 +127,7 @@
 #include "content/public/browser/web_ui_controller.h"
 #include "content/public/common/bindings_policy.h"
 #include "content/public/common/child_process_host.h"
+#include "content/public/common/content_client.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/common/content_features.h"
 #include "content/public/common/content_switches.h"