Implement a salt for MediaSource IDs that can be cleared by a user.

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index d7320889837f7d5518e9d740eae6f27e33113a87..66f11c74b5edb3460364a25e6e344f4ae3c5d083 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -48,6 +48,7 @@
 #include "chrome/browser/guestview/guestview_constants.h"
 #include "chrome/browser/guestview/webview/webview_guest.h"
 #include "chrome/browser/media/media_capture_devices_dispatcher.h"
+#include "chrome/browser/media/media_device_id_salt.h"
 #include "chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h"
 #include "chrome/browser/nacl_host/nacl_browser_delegate_impl.h"
 #include "chrome/browser/nacl_host/nacl_host_message_filter.h"
@@ -2384,6 +2385,13 @@ std::string ChromeContentBrowserClient::GetDefaultDownloadName() {
   return l10n_util::GetStringUTF8(IDS_DEFAULT_DOWNLOAD_FILENAME);
 }
 
+std::string ChromeContentBrowserClient::GetMediaDeviceIDSalt(
+    content::ResourceContext* rc) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  ProfileIOData* io_data = ProfileIOData::FromResourceContext(rc);
+  return io_data->GetMediaDeviceIDSalt();
+}
+
 void ChromeContentBrowserClient::DidCreatePpapiPlugin(
     content::BrowserPpapiHost* browser_host) {
 #if defined(ENABLE_PLUGINS)