Move GetFetchClientSettingsObject() to FetchContext

As preparation for plumbing FetchClientSettingsObject via
FetchContext rather than as an argument,
this CL exposes GetFetchClientSettingsObject() in FetchContext.

NullFetchContext is added just to make
FetchContext::GetFetchClientSettingsObject() abstract and
FetchContext::NullInstance()'s GetFetchClientSettingsObject()
non-null.

This CL doesn't change the behavior.

Bug: 880027
Change-Id: I02a428d77d202ab88cffd22a3fdf3cd34eff4aca
Reviewed-on: https://chromium-review.googlesource.com/c/1200042Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606759}

third_party/blink/renderer/core/loader/base_fetch_context.h

@@ -48,8 +48,6 @@ class CORE_EXPORT BaseFetchContext : public FetchContext {
 
   void Trace(blink::Visitor*) override;
 
-  virtual const FetchClientSettingsObject* GetFetchClientSettingsObject()
-      const = 0;
   virtual KURL GetSiteForCookies() const = 0;
   virtual SubresourceFilter* GetSubresourceFilter() const = 0;
   virtual PreviewsResourceLoadingHints* GetPreviewsResourceLoadingHints()

third_party/blink/renderer/platform/loader/fetch/fetch_context.cc

@@ -30,14 +30,45 @@
 
 #include "third_party/blink/renderer/platform/loader/fetch/fetch_context.h"
 
+#include "third_party/blink/renderer/platform/loader/fetch/fetch_client_settings_object_snapshot.h"
 #include "third_party/blink/renderer/platform/platform_probe_sink.h"
 #include "third_party/blink/renderer/platform/probe/platform_trace_events_agent.h"
 
 namespace blink {
 
+namespace {
+
+class NullFetchContext final : public FetchContext {
+ public:
+  explicit NullFetchContext(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner)
+      : FetchContext(std::move(task_runner)),
+        fetch_client_settings_object_(
+            MakeGarbageCollected<FetchClientSettingsObjectSnapshot>(
+                KURL(),
+                nullptr /* security_origin */,
+                kReferrerPolicyDefault,
+                String())) {}
+
+  const FetchClientSettingsObject* GetFetchClientSettingsObject()
+      const override {
+    return fetch_client_settings_object_;
+  }
+
+  void Trace(blink::Visitor* visitor) override {
+    visitor->Trace(fetch_client_settings_object_);
+    FetchContext::Trace(visitor);
+  }
+
+ private:
+  const Member<const FetchClientSettingsObject> fetch_client_settings_object_;
+};
+
+}  // namespace
+
 FetchContext& FetchContext::NullInstance(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
-  return *(new FetchContext(std::move(task_runner)));
+  return *(new NullFetchContext(std::move(task_runner)));
 }
 
 FetchContext::FetchContext(

third_party/blink/renderer/platform/loader/fetch/fetch_context.h

@@ -62,6 +62,7 @@
 namespace blink {
 
 class ClientHintsPreferences;
+class FetchClientSettingsObject;
 class KURL;
 class MHTMLArchive;
 class PlatformProbeSink;
@@ -107,6 +108,9 @@ class PLATFORM_EXPORT FetchContext
 
   virtual void AddAdditionalRequestHeaders(ResourceRequest&, FetchResourceType);
 
+  virtual const FetchClientSettingsObject* GetFetchClientSettingsObject()
+      const = 0;
+
   // Called when the ResourceFetcher observes a data: URI load that contains an
   // octothorpe ('#') character. This is a temporary method to support an Intent
   // to Deprecate for spec incompliant handling of '#' characters in data URIs.

third_party/blink/renderer/platform/loader/testing/mock_fetch_context.h

@@ -10,6 +10,7 @@
 #include "third_party/blink/public/platform/platform.h"
 #include "third_party/blink/public/platform/web_url_loader_factory.h"
 #include "third_party/blink/renderer/platform/exported/wrapped_resource_request.h"
+#include "third_party/blink/renderer/platform/loader/fetch/fetch_client_settings_object_snapshot.h"
 #include "third_party/blink/renderer/platform/loader/fetch/fetch_context.h"
 #include "third_party/blink/renderer/platform/loader/fetch/fetch_parameters.h"
 #include "third_party/blink/renderer/platform/loader/fetch/resource_timing_info.h"
@@ -53,6 +54,12 @@ class MockFetchContext : public FetchContext {
     security_origin_ = security_origin;
   }
 
+  const FetchClientSettingsObject* GetFetchClientSettingsObject()
+      const override {
+    return new FetchClientSettingsObjectSnapshot(
+        KURL(), security_origin_, kReferrerPolicyDefault, String());
+  }
+
   // The last ResourceRequest passed to DispatchWillSendRequest.
   base::Optional<ResourceRequest> RequestFromWillSendRequest() const {
     return will_send_request_;