Add sampling of unknown filetypes in download protection.

chrome/common/safe_browsing/file_type_policies.cc

Index: chrome/common/safe_browsing/file_type_policies.cc
diff --git a/chrome/common/safe_browsing/file_type_policies.cc b/chrome/common/safe_browsing/file_type_policies.cc
index 1741b5a88de3e1ab7ba2d6fc3879bbca939b9460..fb0c1a096560ddcafc85d33445880d8e7fd811fe 100644
--- a/chrome/common/safe_browsing/file_type_policies.cc
+++ b/chrome/common/safe_browsing/file_type_policies.cc
@@ -22,19 +22,30 @@ struct FileTypePoliciesSingletonTrait
     : public base::DefaultSingletonTraits<FileTypePolicies> {
   static FileTypePolicies* New() {
     FileTypePolicies* instance = new FileTypePolicies();
+    // If you change this, you may want to update FileTypePoliciesTestOverlay.
     instance->PopulateFromResourceBundle();
     return instance;
   }
 };
 
 // --- FileTypePolicies methods ---
+//
+
+FileTypePolicies* FileTypePolicies::instance_for_tests_ = 0;

[asanka, 2016/06/20 18:15:46]

Nit: nullptr

[Nathan Parker, 2016/06/20 22:47:31]

Done.

 
 // static
 FileTypePolicies* FileTypePolicies::GetInstance() {
+  if (instance_for_tests_)
+    return instance_for_tests_;
+
   return base::Singleton<FileTypePolicies,
                          FileTypePoliciesSingletonTrait>::get();
 }
 
+void FileTypePolicies::SetInstanceForTests(FileTypePolicies* instance) {
+  instance_for_tests_ = instance;
+}
+
 FileTypePolicies::FileTypePolicies() {
   // Setup a file-type policy to use if the ResourceBundle is unreadable.
   // This should normally never be used.
@@ -128,22 +139,36 @@ FileTypePolicies::UpdateResult FileTypePolicies::PopulateFromBinaryPb(
 
   // Looks good. Update our internal list.
   config_.reset(new_config.release());
+  BuildIndex();
 
+  return UpdateResult::SUCCESS;
+}
+
+void FileTypePolicies::BuildIndex() {
+  lock_.AssertAcquired();
   // Build an index for faster lookup.
   file_type_by_ext_.clear();
   for (const DownloadFileType& file_type : config_->file_types()) {
     // If there are dups, first one wins.
     file_type_by_ext_.insert(std::make_pair(file_type.extension(), &file_type));
   }
+}
 
-  return UpdateResult::SUCCESS;
+// For testing.
+void FileTypePolicies::SetConfigForTesting(
+    const DownloadFileTypeConfig& new_config) {
+  AutoLock lock(lock_);
+  config_->CopyFrom(new_config);
+  BuildIndex();
 }
 
-float FileTypePolicies::SampledPingProbability() const {
+// For testing.
+DownloadFileTypeConfig FileTypePolicies::GetConfigForTesting() const {
   AutoLock lock(lock_);
-  return config_ ? config_->sampled_ping_probability() : 0.0;
+  return *config_;
 }
 
+
 // static
 base::FilePath::StringType FileTypePolicies::GetFileExtension(
     const base::FilePath& file) {
@@ -166,6 +191,15 @@ std::string FileTypePolicies::CanonicalizedExtension(
   return ascii_ext;
 }
 
+//
+// Accessors
+//
+
+float FileTypePolicies::SampledPingProbability() const {
+  AutoLock lock(lock_);
+  return config_ ? config_->sampled_ping_probability() : 0.0;
+}
+
 const DownloadFileType& FileTypePolicies::PolicyForExtension(
     const std::string& ascii_ext) const {
   lock_.AssertAcquired();
@@ -208,11 +242,7 @@ bool FileTypePolicies::IsArchiveFile(const base::FilePath& file) const {
   return PolicyForExtension(ext).is_archive();
 }
 
-bool FileTypePolicies::IsCheckedBinaryFile(const base::FilePath& file) const {
-  const std::string ext = CanonicalizedExtension(file);
-  AutoLock lock(lock_);
-  return PolicyForExtension(ext).ping_setting() == DownloadFileType::FULL_PING;
-}
+// TODO(nparker): Add unit tests for these accessors.
 
 bool FileTypePolicies::IsAllowedToOpenAutomatically(
     const base::FilePath& file) const {
@@ -224,6 +254,17 @@ bool FileTypePolicies::IsAllowedToOpenAutomatically(
          DownloadFileType::ALLOW_AUTO_OPEN;
 }
 
+DownloadFileType::PingSetting FileTypePolicies::PingSettingForFile(
+    const base::FilePath& file) const {
+  const std::string ext = CanonicalizedExtension(file);
+  AutoLock lock(lock_);
+  return PolicyForExtension(ext).ping_setting();
+}
+
+bool FileTypePolicies::IsCheckedBinaryFile(const base::FilePath& file) const {
+  return PingSettingForFile(file) == DownloadFileType::FULL_PING;
+}
+
 DownloadFileType::DangerLevel FileTypePolicies::GetFileDangerLevel(
     const base::FilePath& file) const {
   const std::string ext = CanonicalizedExtension(file);