Add throttling to corrupt policy extensions reinstall

chrome/browser/extensions/chrome_content_verifier_delegate.h

 // Copyright 2015 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_CHROME_CONTENT_VERIFIER_DELEGATE_H_
 #define CHROME_BROWSER_EXTENSIONS_CHROME_CONTENT_VERIFIER_DELEGATE_H_
 
+#include <map>
+#include <memory>
 #include <set>
 #include <string>
 
+#include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "extensions/browser/content_verifier_delegate.h"
 
 namespace content {
 class BrowserContext;
 }
 
+namespace net {
+class BackoffEntry;
+}
+
 namespace extensions {
 
 class ChromeContentVerifierDelegate : public ContentVerifierDelegate {
  public:
   static Mode GetDefaultMode();
 
   explicit ChromeContentVerifierDelegate(content::BrowserContext* context);
 
   ~ChromeContentVerifierDelegate() override;
 
   // ContentVerifierDelegate:
   Mode ShouldBeVerified(const Extension& extension) override;
   ContentVerifierKey GetPublicKey() override;
   GURL GetSignatureFetchUrl(const std::string& extension_id,
                             const base::Version& version) override;
   std::set<base::FilePath> GetBrowserImagePaths(
       const extensions::Extension* extension) override;
   void VerifyFailed(const std::string& extension_id,
                     ContentVerifyJob::FailureReason reason) override;
 
+ protected:
+  FRIEND_TEST_ALL_PREFIXES(ContentVerifierPolicyTest, Backoff);
+  // For tests, overrides the default action to take to initiate policy
+  // force-reinstalls.
+  static void set_policy_reinstall_action_for_test(
+      base::Callback<void(base::TimeDelta delay)>* action);
+
  private:
   content::BrowserContext* context_;
   ContentVerifierDelegate::Mode default_mode_;
 
+  // This maps an extension id to a backoff entry for slowing down
+  // redownload/reinstall of corrupt policy extensions if it keeps happening
+  // in a loop (eg crbug.com/661738).
+  std::map<std::string, std::unique_ptr<net::BackoffEntry>>
+      policy_reinstall_backoff_;
+
   // For reporting metrics in BOOTSTRAP mode, when an extension would be
   // disabled if content verification was in ENFORCE mode.
   std::set<std::string> would_be_disabled_ids_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeContentVerifierDelegate);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CHROME_CONTENT_VERIFIER_DELEGATE_H_