Revert of Make default media device ID salts random by default

content/browser/resource_context_impl.cc

Index: content/browser/resource_context_impl.cc
diff --git a/content/browser/resource_context_impl.cc b/content/browser/resource_context_impl.cc
index 4a107dc9a45c9455caef31f445c4e48460d2476d..e7aa29b9570d5706018be8032db33507b15392f9 100644
--- a/content/browser/resource_context_impl.cc
+++ b/content/browser/resource_context_impl.cc
@@ -6,11 +6,9 @@
 
 #include <stdint.h>
 
-#include "base/base64.h"
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
-#include "base/rand_util.h"
 #include "content/browser/blob_storage/chrome_blob_storage_context.h"
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
 #include "content/browser/loader/resource_request_info_impl.h"
@@ -25,13 +23,22 @@
 
 namespace content {
 
+namespace {
+
 // Key names on ResourceContext.
 const char kBlobStorageContextKeyName[] = "content_blob_storage_context";
 const char kStreamContextKeyName[] = "content_stream_context";
 const char kURLDataManagerBackendKeyName[] = "url_data_manager_backend";
 
-ResourceContext::ResourceContext()
-    : media_device_id_salt_(CreateRandomMediaDeviceIDSalt()) {
+// Used by the default implementation of GetMediaDeviceIDSalt, below.
+std::string ReturnEmptySalt() {
+  return std::string();
+}
+
+}  // namespace
+
+
+ResourceContext::ResourceContext() {
   ResourceDispatcherHostImpl* rdhi = ResourceDispatcherHostImpl::Get();
   if (rdhi) {
     BrowserThread::PostTask(
@@ -52,8 +59,8 @@
   DetachUserDataThread();
 }
 
-std::string ResourceContext::GetMediaDeviceIDSalt() {
-  return media_device_id_salt_;
+ResourceContext::SaltCallback ResourceContext::GetMediaDeviceIDSalt() {
+  return base::Bind(&ReturnEmptySalt);
 }
 
 std::unique_ptr<net::ClientCertStore> ResourceContext::CreateClientCertStore() {
@@ -67,14 +74,6 @@
     const base::Callback<void(std::unique_ptr<net::KeygenHandler>)>& callback) {
   callback.Run(base::WrapUnique(
       new net::KeygenHandler(key_size_in_bits, challenge_string, url)));
-}
-
-// static
-std::string ResourceContext::CreateRandomMediaDeviceIDSalt() {
-  std::string salt;
-  base::Base64Encode(base::RandBytesAsString(16), &salt);
-  DCHECK(!salt.empty());
-  return salt;
 }
 
 ChromeBlobStorageContext* GetChromeBlobStorageContextForResourceContext(