Add the client for accessing Subresource Filter only list.

components/subresource_filter/content/browser/subresource_filter_activation_navigation_throttle.cc

+// Copyright (c) 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/subresource_filter/content/browser/subresource_filter_activation_navigation_throttle.h"
+
+#include "components/safe_browsing_db/v4_local_database_manager.h"
+#include "components/subresource_filter/content/browser/content_subresource_filter_driver_factory.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/navigation_handle.h"
+#include "content/public/browser/web_contents.h"
+
+namespace {
+
+// Maximum time in milliseconds to wait for the safe browsing service to
+// verify a URL. After this amount of time the outstanding check will be
+// aborted, and the URL will be treated as if it doesn't belong to the
+// Subresource Filter only list.
+const int kCheckUrlTimeoutMs = 5000;
+
+}  // namespace
+
+namespace subresource_filter {
+
+SubresourceFilterActivationNavigationThrottle::
+    SubresourceFilterActivationNavigationThrottle(
+        content::NavigationHandle* handle,
+        const scoped_refptr<safe_browsing::SafeBrowsingDatabaseManager>&
+            database_manager)
+    : NavigationThrottle(handle), database_manager_(database_manager) {}
+
+SubresourceFilterActivationNavigationThrottle::
+    ~SubresourceFilterActivationNavigationThrottle() {}
+
+content::NavigationThrottle::ThrottleCheckResult
+SubresourceFilterActivationNavigationThrottle::WillProcessResponse() {
+  content::BrowserThread::PostTask(
+      content::BrowserThread::IO, FROM_HERE,
+      base::Bind(&SubresourceFilterActivationNavigationThrottle::CheckUrlOnIO,
+                 base::Unretained(this), navigation_handle()->GetURL()));
+  return content::NavigationThrottle::ThrottleCheckResult::DEFER;
+}
+
+void SubresourceFilterActivationNavigationThrottle::CheckUrlOnIO(
+    const GURL& url) {
+  url_being_checked_ = url;
+  if (database_manager_->CheckUrlForSubresourceFilter(url, this)) {
+    content::BrowserThread::PostTask(
+        content::BrowserThread::UI, FROM_HERE,
+        base::Bind(&SubresourceFilterActivationNavigationThrottle::
+                       OnCheckUrlResultOnUI,
+                   AsWeakPtr(), url, safe_browsing::SB_THREAT_TYPE_SAFE,
+                   safe_browsing::ThreatPatternType::NONE));
+  }
+  timer_.Start(
+      FROM_HERE, base::TimeDelta::FromMilliseconds(kCheckUrlTimeoutMs), this,
+      &SubresourceFilterActivationNavigationThrottle::OnCheckUrlTimeout);
+}
+
+// SafeBrowsingService::Client implementation, called on the IO thread once

[engedy, 2017/02/17 20:50:52]

nit: I'd just remove this comment (sign) when we already have the DCHECK (cop). 

[melandory, 2017/02/28 12:16:05]

Done.

+// the URL has been classified.
+void SubresourceFilterActivationNavigationThrottle::OnCheckBrowseUrlResult(
+    const GURL& url,
+    safe_browsing::SBThreatType threat_type,
+    const safe_browsing::ThreatMetadata& metadata) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+  timer_.Stop();  // Cancel the timeout timer.
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI, FROM_HERE,
+      base::Bind(
+          &SubresourceFilterActivationNavigationThrottle::OnCheckUrlResultOnUI,
+          AsWeakPtr(), url, threat_type, metadata.threat_pattern_type));
+}
+
+void SubresourceFilterActivationNavigationThrottle::OnCheckUrlResultOnUI(
+    const GURL& url,
+    safe_browsing::SBThreatType threat_type,
+    safe_browsing::ThreatPatternType pattern_type) {
+  content::WebContents* web_contents = navigation_handle()->GetWebContents();
+  if (web_contents) {
+    using subresource_filter::ContentSubresourceFilterDriverFactory;
+    ContentSubresourceFilterDriverFactory* driver_factory =
+        ContentSubresourceFilterDriverFactory::FromWebContents(web_contents);
+    DCHECK(driver_factory);
+
+    driver_factory->OnMainResourceMatchedSafeBrowsingBlacklist(
+        url, std::vector<GURL>(), threat_type, pattern_type);
+  }
+  navigation_handle()->Resume();
+}
+
+void SubresourceFilterActivationNavigationThrottle::OnCheckUrlTimeout() {
+  database_manager_->CancelCheck(this);
+
+  OnCheckBrowseUrlResult(url_being_checked_, safe_browsing::SB_THREAT_TYPE_SAFE,
+                         safe_browsing::ThreatMetadata());
+}
+
+}  //  namespace subresource_filter