Add sampling of unknown filetypes in download protection.

chrome/common/safe_browsing/file_type_policies.h

Index: chrome/common/safe_browsing/file_type_policies.h
diff --git a/chrome/common/safe_browsing/file_type_policies.h b/chrome/common/safe_browsing/file_type_policies.h
index f50d3a6ff6feaf13f4a12326ddc72d23a88d1611..29994464061f945620184e2eb1c7405a544a03b2 100644
--- a/chrome/common/safe_browsing/file_type_policies.h
+++ b/chrome/common/safe_browsing/file_type_policies.h
@@ -16,6 +16,7 @@
 namespace safe_browsing {
 
 struct FileTypePoliciesSingletonTrait;
+class FileTypePoliciesTestOverlay;
 
 // This holds a list of file types (aka file extensions) that we know about,
 // with policies related to how Safe Browsing and the download UI should treat
@@ -67,6 +68,10 @@ class FileTypePolicies {
   DownloadFileType::DangerLevel GetFileDangerLevel(
       const base::FilePath& file) const;
 
+  // Return the type of ping we should send for this file
+  DownloadFileType::PingSetting PingSettingForFile(
+      const base::FilePath& file) const;
+
   float SampledPingProbability() const;
 
   DownloadFileType PolicyForFile(const base::FilePath& file) const;
@@ -108,11 +113,23 @@ class FileTypePolicies {
       const std::string& ext) const;
 
  private:
+  // Overrides the global singleton for tests if !=0.  Caller retains ownership
+  // and should reset to 0 when done. Use FileTypePoliciesTestOverlay.
+  static void SetInstanceForTests(FileTypePolicies* instance);
+  static FileTypePolicies* instance_for_tests_;
+
   // Read data from the main ResourceBundle. This updates the internal list
   // only if the data passes integrity checks. This is normally called once
   // after construction.
   void PopulateFromResourceBundle();
 
+  // Recreate file_type_by_ext_ to match config_.
+  void BuildIndex();
+
+  // For testing: Safely replace our config_ with new_config.
+  void SetConfigForTesting(const DownloadFileTypeConfig& new_config);
+  DownloadFileTypeConfig GetConfigForTesting() const;
+
   // The latest config we've committed. Starts out null.
   // Protected by lock_.
   std::unique_ptr<DownloadFileTypeConfig> config_;
@@ -132,6 +149,7 @@ class FileTypePolicies {
   FRIEND_TEST_ALL_PREFIXES(FileTypePoliciesTest, BadUpdateFromExisting);
 
   friend struct FileTypePoliciesSingletonTrait;
+  friend class FileTypePoliciesTestOverlay;
 };
 
 }  // namespace safe_browsing