[OutOfBlinkSandbox] Move SandboxFlags blink=>network (reland)

This reland the following patch:
https://chromium-review.googlesource.com/c/chromium/src/+/2062336

The diff:
https://chromium-review.googlesource.com/c/chromium/src/+/2144100/1..5

The previous CL was reverted because if was not compiling reliably.
The target:
  //third_party/blink/common:common
was missing:
  //services/network/public/mojom:mojom_blink

However, adding it would creates a dependency cycle:

ERROR Dependency cycle:
  //third_party/blink/public/common:common ->
  //third_party/blink/common:common ->
  //services/network/public/mojom:mojom_blink ->
  //mojo/public/cpp/bindings:wtf_support ->
  //third_party/blink/public:blink_headers ->
  //third_party/blink/public/common:common

It means we can never #include a generated .mojom-blink.h from
//third_party/blink/common:common

Fortunately, there are already many .mojom-shared.h there. So
we can can include web_sandbox_flags.mojom-shared.h instead. The enum
definition is entirely contained in this file anyway.

The mojom-shared.h is already a dependency::
/third_party/blink/common:common ->
/services/network/public/cpp:cpp ->
/services/network/public/mojom:mojom [generated HERE]

[email protected]
[email protected],[email protected],[email protected],[email protected],[email protected],[email protected]

Bug: 1041376
Change-Id: I272d4971920d6d3c04a965f1aa9b90376353b446
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2144100
Reviewed-by: Kinuko Yasuda <[email protected]>
Commit-Queue: Arthur Sonzogni <[email protected]>
Cr-Commit-Position: refs/heads/master@{#758153}
diff --git a/content/renderer/render_frame_impl.h b/content/renderer/render_frame_impl.h
index dd2e5ed..1ea217b 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -684,7 +684,7 @@
   void DidChangeFramePolicy(blink::WebFrame* child_frame,
                             const blink::FramePolicy& frame_policy) override;
   void DidSetFramePolicyHeaders(
-      blink::mojom::WebSandboxFlags flags,
+      network::mojom::WebSandboxFlags flags,
       const blink::ParsedFeaturePolicy& fp_header,
       const blink::DocumentPolicy::FeatureState& dp_header) override;
   void DidChangeFrameOwnerProperties(