Merge 251024 "Allow retrieval of media device ID salt even after..."

> Allow retrieval of media device ID salt even after ResourceContext has gone away.
> 
> TBR=willchan@chromium.org
> BUG=341211
> 
> Review URL: https://codereview.chromium.org/143003031

TBR=joi@chromium.org

Review URL: https://codereview.chromium.org/169553002

git-svn-id: svn://svn.chromium.org/chrome/branches/1750/src@251660 0039d316-1c4b-4281-b951-d872f2087c98

18 files changed, 119 insertions, 88 deletions

diff --git a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
index 602e857..e8ab7a5 100644
--- a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
+++ b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
@@ -314,7 +314,7 @@ WebrtcAudioPrivateGetAssociatedSinkFunction::GetRawSourceIDOnIOThread(
        ++it) {
     const std::string& id = it->unique_id;
     if (content::DoesMediaDeviceIDMatchHMAC(
-            context,
+            context->GetMediaDeviceIDSalt(),
             security_origin,
             source_id_in_origin,
             id)) {
diff --git a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_browsertest.cc b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_browsertest.cc
index e3f7c7e..904b1ad 100644
--- a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_browsertest.cc
+++ b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_browsertest.cc
@@ -132,7 +132,7 @@ class WebrtcAudioPrivateTest : public AudioWaitingExtensionTest {
      enumeration_event_.Wait();
     } else {
       *source_id_in_origin = content::GetHMACForMediaDeviceID(
-          resource_context,
+          resource_context->GetMediaDeviceIDSalt(),
           origin,
           raw_device_id);
       enumeration_event_.Signal();
diff --git a/chrome/browser/media/media_device_id_salt.h b/chrome/browser/media/media_device_id_salt.h
index a98e3fb..46df854 100644
--- a/chrome/browser/media/media_device_id_salt.h
+++ b/chrome/browser/media/media_device_id_salt.h
@@ -7,6 +7,7 @@
 
 #include <string>
 
+#include "base/memory/ref_counted.h"
 #include "base/prefs/pref_member.h"
 #include "components/user_prefs/pref_registry_syncable.h"
 
@@ -15,11 +16,12 @@ class PrefService;
 // MediaDeviceIDSalt is responsible for creating and retrieving a salt string
 // that is used for creating MediaSource IDs that can be cached by a web
 // service. If the cache is cleared, the  MediaSourceIds are invalidated.
-class MediaDeviceIDSalt {
+//
+// The class is reference counted so that it can be used in the
+// callback returned by ResourceContext::GetMediaDeviceIDSalt.
+class MediaDeviceIDSalt : public base::RefCountedThreadSafe<MediaDeviceIDSalt> {
  public:
-  MediaDeviceIDSalt(PrefService* pref_service,
-                    bool incognito);
-  ~MediaDeviceIDSalt();
+  MediaDeviceIDSalt(PrefService* pref_service, bool incognito);
   void ShutdownOnUIThread();
 
   std::string GetSalt() const;
@@ -28,6 +30,9 @@ class MediaDeviceIDSalt {
   static void Reset(PrefService* pref_service);
 
  private:
+  friend class base::RefCountedThreadSafe<MediaDeviceIDSalt>;
+  ~MediaDeviceIDSalt();
+
   // |incognito_salt_| is initialized in ctor on UI thread but only read
   //  on the IO thread.
   std::string incognito_salt_;
diff --git a/chrome/browser/profiles/profile_io_data.cc b/chrome/browser/profiles/profile_io_data.cc
index a9f68c4..49aa9f0 100644
--- a/chrome/browser/profiles/profile_io_data.cc
+++ b/chrome/browser/profiles/profile_io_data.cc
@@ -478,8 +478,7 @@ void ProfileIOData::InitializeOnUIThread(Profile* profile) {
     signin_allowed_.MoveToThread(io_message_loop_proxy);
   }
 
-  media_device_id_salt_.reset(new MediaDeviceIDSalt(pref_service,
-                                                    is_incognito()));
+  media_device_id_salt_ = new MediaDeviceIDSalt(pref_service, is_incognito());
 
 #if defined(OS_CHROMEOS)
   cert_verifier_ = policy::PolicyCertServiceFactory::CreateForProfile(profile);
@@ -780,8 +779,8 @@ HostContentSettingsMap* ProfileIOData::GetHostContentSettingsMap() const {
   return host_content_settings_map_.get();
 }
 
-std::string ProfileIOData::GetMediaDeviceIDSalt() const {
-  return media_device_id_salt_->GetSalt();
+ResourceContext::SaltCallback ProfileIOData::GetMediaDeviceIDSalt() const {
+  return base::Bind(&MediaDeviceIDSalt::GetSalt, media_device_id_salt_);
 }
 
 void ProfileIOData::InitializeMetricsEnabledStateOnUIThread() {
@@ -919,7 +918,8 @@ bool ProfileIOData::ResourceContext::AllowContentAccess(
   return setting == CONTENT_SETTING_ALLOW;
 }
 
-std::string ProfileIOData::ResourceContext::GetMediaDeviceIDSalt() {
+ResourceContext::SaltCallback
+ProfileIOData::ResourceContext::GetMediaDeviceIDSalt() {
   return io_data_->GetMediaDeviceIDSalt();
 }
 
diff --git a/chrome/browser/profiles/profile_io_data.h b/chrome/browser/profiles/profile_io_data.h
index 5c98b26..d56b42e 100644
--- a/chrome/browser/profiles/profile_io_data.h
+++ b/chrome/browser/profiles/profile_io_data.h
@@ -176,7 +176,7 @@ class ProfileIOData {
     return &signin_allowed_;
   }
 
-  std::string GetMediaDeviceIDSalt() const;
+  content::ResourceContext::SaltCallback GetMediaDeviceIDSalt() const;
 
   net::TransportSecurityState* transport_security_state() const {
     return transport_security_state_.get();
@@ -383,7 +383,7 @@ class ProfileIOData {
         OVERRIDE;
     virtual bool AllowMicAccess(const GURL& origin) OVERRIDE;
     virtual bool AllowCameraAccess(const GURL& origin) OVERRIDE;
-    virtual std::string GetMediaDeviceIDSalt() OVERRIDE;
+    virtual SaltCallback GetMediaDeviceIDSalt() OVERRIDE;
 
    private:
     friend class ProfileIOData;
@@ -485,7 +485,7 @@ class ProfileIOData {
 
   mutable StringListPrefMember one_click_signin_rejected_email_list_;
 
-  mutable scoped_ptr<MediaDeviceIDSalt> media_device_id_salt_;
+  mutable scoped_refptr<MediaDeviceIDSalt> media_device_id_salt_;
 
   // Member variables which are pointed to by the various context objects.
   mutable BooleanPrefMember enable_referrers_;
diff --git a/content/browser/loader/resource_scheduler_unittest.cc b/content/browser/loader/resource_scheduler_unittest.cc
index 07dd333..fbdc72b 100644
--- a/content/browser/loader/resource_scheduler_unittest.cc
+++ b/content/browser/loader/resource_scheduler_unittest.cc
@@ -92,7 +92,6 @@ class FakeResourceContext : public ResourceContext {
   virtual net::URLRequestContext* GetRequestContext() OVERRIDE { return NULL; }
   virtual bool AllowMicAccess(const GURL& origin) OVERRIDE { return false; }
   virtual bool AllowCameraAccess(const GURL& origin) OVERRIDE { return false; }
-  virtual std::string GetMediaDeviceIDSalt() OVERRIDE { return std::string(); }
 };
 
 class FakeResourceMessageFilter : public ResourceMessageFilter {
diff --git a/content/browser/renderer_host/media/device_request_message_filter.cc b/content/browser/renderer_host/media/device_request_message_filter.cc
index 37e3bea..89e632f 100644
--- a/content/browser/renderer_host/media/device_request_message_filter.cc
+++ b/content/browser/renderer_host/media/device_request_message_filter.cc
@@ -30,7 +30,9 @@ DeviceRequestMessageFilter::DeviceRequestMessageFilter(
 }
 
 DeviceRequestMessageFilter::~DeviceRequestMessageFilter() {
-  DCHECK(requests_.empty());
+  // CHECK rather than DCHECK to make sure this never happens in the
+  // wild. We want to be sure due to http://crbug.com/341211
+  CHECK(requests_.empty());
 }
 
 struct DeviceRequestMessageFilter::DeviceRequest {
@@ -134,14 +136,14 @@ void DeviceRequestMessageFilter::OnGetSources(int request_id,
                                               const GURL& security_origin) {
   // Make request to get audio devices.
   const std::string& audio_label = media_stream_manager_->EnumerateDevices(
-      this, -1, -1, resource_context_, -1, MEDIA_DEVICE_AUDIO_CAPTURE,
-      security_origin);
+      this, -1, -1, resource_context_->GetMediaDeviceIDSalt(), -1,
+      MEDIA_DEVICE_AUDIO_CAPTURE, security_origin);
   DCHECK(!audio_label.empty());
 
   // Make request for video devices.
   const std::string& video_label = media_stream_manager_->EnumerateDevices(
-      this, -1, -1, resource_context_, -1, MEDIA_DEVICE_VIDEO_CAPTURE,
-      security_origin);
+      this, -1, -1, resource_context_->GetMediaDeviceIDSalt(), -1,
+      MEDIA_DEVICE_VIDEO_CAPTURE, security_origin);
   DCHECK(!video_label.empty());
 
   requests_.push_back(DeviceRequest(
diff --git a/content/browser/renderer_host/media/device_request_message_filter_unittest.cc b/content/browser/renderer_host/media/device_request_message_filter_unittest.cc
index 3a9382b..95b9cd8 100644
--- a/content/browser/renderer_host/media/device_request_message_filter_unittest.cc
+++ b/content/browser/renderer_host/media/device_request_message_filter_unittest.cc
@@ -29,7 +29,7 @@ class MockMediaStreamManager : public MediaStreamManager {
                std::string(MediaStreamRequester* requester,
                            int render_process_id,
                            int render_view_id,
-                           ResourceContext* rc,
+                           const ResourceContext::SaltCallback& rc,
                            int page_request_id,
                            MediaStreamType type,
                            const GURL& security_origin));
@@ -38,7 +38,7 @@ class MockMediaStreamManager : public MediaStreamManager {
   std::string DoEnumerateDevices(MediaStreamRequester* requester,
                                  int render_process_id,
                                  int render_view_id,
-                                 ResourceContext* rc,
+                                 const ResourceContext::SaltCallback& rc,
                                  int page_request_id,
                                  MediaStreamType type,
                                  const GURL& security_origin) {
diff --git a/content/browser/renderer_host/media/media_stream_dispatcher_host.cc b/content/browser/renderer_host/media/media_stream_dispatcher_host.cc
index 8ea1617..2385f3b 100644
--- a/content/browser/renderer_host/media/media_stream_dispatcher_host.cc
+++ b/content/browser/renderer_host/media/media_stream_dispatcher_host.cc
@@ -131,7 +131,8 @@ void MediaStreamDispatcherHost::OnGenerateStream(
            << security_origin.spec() << ")";
 
   media_stream_manager_->GenerateStream(
-      this, render_process_id_, render_view_id, resource_context_,
+      this, render_process_id_, render_view_id,
+      resource_context_->GetMediaDeviceIDSalt(),
       page_request_id,
       components, security_origin);
 }
@@ -167,7 +168,8 @@ void MediaStreamDispatcherHost::OnEnumerateDevices(
            << security_origin.spec() << ")";
 
   media_stream_manager_->EnumerateDevices(
-      this, render_process_id_, render_view_id, resource_context_,
+      this, render_process_id_, render_view_id,
+      resource_context_->GetMediaDeviceIDSalt(),
       page_request_id, type, security_origin);
 }
 
@@ -195,7 +197,8 @@ void MediaStreamDispatcherHost::OnOpenDevice(
            << security_origin.spec() << ")";
 
   media_stream_manager_->OpenDevice(
-      this, render_process_id_, render_view_id, resource_context_,
+      this, render_process_id_, render_view_id,
+      resource_context_->GetMediaDeviceIDSalt(),
       page_request_id, device_id, type, security_origin);
 
 }
diff --git a/content/browser/renderer_host/media/media_stream_dispatcher_host_unittest.cc b/content/browser/renderer_host/media/media_stream_dispatcher_host_unittest.cc
index b8c4f25..956b0cd 100644
--- a/content/browser/renderer_host/media/media_stream_dispatcher_host_unittest.cc
+++ b/content/browser/renderer_host/media/media_stream_dispatcher_host_unittest.cc
@@ -332,10 +332,10 @@ class MediaStreamDispatcherHostTest : public testing::Test {
           physical_audio_devices_.begin();
       for (; audio_it != physical_audio_devices_.end(); ++audio_it) {
         if (content::DoesMediaDeviceIDMatchHMAC(
-            browser_context_.GetResourceContext(),
-            origin,
-            devices[i].device.id,
-            audio_it->unique_id)) {
+                browser_context_.GetResourceContext()->GetMediaDeviceIDSalt(),
+                origin,
+                devices[i].device.id,
+                audio_it->unique_id)) {
           EXPECT_FALSE(found_match);
           found_match = true;
         }
@@ -344,10 +344,10 @@ class MediaStreamDispatcherHostTest : public testing::Test {
           physical_video_devices_.begin();
       for (; video_it != physical_video_devices_.end(); ++video_it) {
         if (content::DoesMediaDeviceIDMatchHMAC(
-            browser_context_.GetResourceContext(),
-            origin,
-            devices[i].device.id,
-            video_it->id())) {
+                browser_context_.GetResourceContext()->GetMediaDeviceIDSalt(),
+                origin,
+                devices[i].device.id,
+                video_it->id())) {
           EXPECT_FALSE(found_match);
           found_match = true;
         }
@@ -537,7 +537,7 @@ TEST_F(MediaStreamDispatcherHostTest, GenerateStreamsWithMandatorySourceId) {
       physical_audio_devices_.begin();
   for (; audio_it != physical_audio_devices_.end(); ++audio_it) {
     std::string source_id = content::GetHMACForMediaDeviceID(
-        browser_context_.GetResourceContext(),
+        browser_context_.GetResourceContext()->GetMediaDeviceIDSalt(),
         origin_,
         audio_it->unique_id);
     ASSERT_FALSE(source_id.empty());
@@ -553,7 +553,7 @@ TEST_F(MediaStreamDispatcherHostTest, GenerateStreamsWithMandatorySourceId) {
       physical_video_devices_.begin();
   for (; video_it != physical_video_devices_.end(); ++video_it) {
     std::string source_id = content::GetHMACForMediaDeviceID(
-        browser_context_.GetResourceContext(),
+        browser_context_.GetResourceContext()->GetMediaDeviceIDSalt(),
         origin_,
         video_it->id());
     ASSERT_FALSE(source_id.empty());
@@ -576,7 +576,7 @@ TEST_F(MediaStreamDispatcherHostTest, GenerateStreamsWithOptionalSourceId) {
       physical_audio_devices_.begin();
   for (; audio_it != physical_audio_devices_.end(); ++audio_it) {
     std::string source_id = content::GetHMACForMediaDeviceID(
-        browser_context_.GetResourceContext(),
+        browser_context_.GetResourceContext()->GetMediaDeviceIDSalt(),
         origin_,
         audio_it->unique_id);
     ASSERT_FALSE(source_id.empty());
@@ -592,7 +592,7 @@ TEST_F(MediaStreamDispatcherHostTest, GenerateStreamsWithOptionalSourceId) {
       physical_video_devices_.begin();
   for (; video_it != physical_video_devices_.end(); ++video_it) {
     std::string source_id = content::GetHMACForMediaDeviceID(
-        browser_context_.GetResourceContext(),
+        browser_context_.GetResourceContext()->GetMediaDeviceIDSalt(),
         origin_,
         video_it->id());
     ASSERT_FALSE(source_id.empty());
diff --git a/content/browser/renderer_host/media/media_stream_manager.cc b/content/browser/renderer_host/media/media_stream_manager.cc
index ab61b28..f6f62fd 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -103,6 +103,11 @@ void ParseStreamType(const StreamOptions& options,
   }
 }
 
+// Needed for MediaStreamManager::GenerateStream below.
+std::string ReturnEmptySalt() {
+  return std::string();
+}
+
 }  // namespace
 
 
@@ -121,7 +126,7 @@ class MediaStreamManager::DeviceRequest {
                 const GURL& security_origin,
                 MediaStreamRequestType request_type,
                 const StreamOptions& options,
-                ResourceContext* resource_context)
+                const ResourceContext::SaltCallback& salt_callback)
       : requester(requester),
         requesting_process_id(requesting_process_id),
         requesting_view_id(requesting_view_id),
@@ -129,7 +134,7 @@ class MediaStreamManager::DeviceRequest {
         security_origin(security_origin),
         request_type(request_type),
         options(options),
-        resource_context(resource_context),
+        salt_callback(salt_callback),
         state_(NUM_MEDIA_TYPES, MEDIA_REQUEST_STATE_NOT_REQUESTED),
         audio_type_(MEDIA_NO_SERVICE),
         video_type_(MEDIA_NO_SERVICE) {
@@ -249,7 +254,7 @@ class MediaStreamManager::DeviceRequest {
 
   const StreamOptions options;
 
-  ResourceContext* resource_context;
+  ResourceContext::SaltCallback salt_callback;
 
   StreamDeviceInfoArray devices;
 
@@ -337,7 +342,7 @@ std::string MediaStreamManager::MakeMediaAccessRequest(
                                              security_origin,
                                              MEDIA_DEVICE_ACCESS,
                                              options,
-                                             NULL);
+                                             base::Bind(&ReturnEmptySalt));
 
   const std::string& label = AddRequest(request);
 
@@ -357,7 +362,7 @@ std::string MediaStreamManager::MakeMediaAccessRequest(
 void MediaStreamManager::GenerateStream(MediaStreamRequester* requester,
                                         int render_process_id,
                                         int render_view_id,
-                                        ResourceContext* rc,
+                                        const ResourceContext::SaltCallback& sc,
                                         int page_request_id,
                                         const StreamOptions& options,
                                         const GURL& security_origin) {
@@ -375,7 +380,7 @@ void MediaStreamManager::GenerateStream(MediaStreamRequester* requester,
                                              security_origin,
                                              MEDIA_GENERATE_STREAM,
                                              options,
-                                             rc);
+                                             sc);
 
   const std::string& label = AddRequest(request);
 
@@ -536,7 +541,7 @@ std::string MediaStreamManager::EnumerateDevices(
     MediaStreamRequester* requester,
     int render_process_id,
     int render_view_id,
-    ResourceContext* rc,
+    const ResourceContext::SaltCallback& sc,
     int page_request_id,
     MediaStreamType type,
     const GURL& security_origin) {
@@ -552,7 +557,7 @@ std::string MediaStreamManager::EnumerateDevices(
                                              security_origin,
                                              MEDIA_ENUMERATE_DEVICES,
                                              StreamOptions(),
-                                             rc);
+                                             sc);
   if (IsAudioMediaType(type))
     request->SetAudioType(type);
   else if (IsVideoMediaType(type))
@@ -603,7 +608,7 @@ void MediaStreamManager::DoEnumerateDevices(const std::string& label) {
 void MediaStreamManager::OpenDevice(MediaStreamRequester* requester,
                                     int render_process_id,
                                     int render_view_id,
-                                    ResourceContext* rc,
+                                    const ResourceContext::SaltCallback& sc,
                                     int page_request_id,
                                     const std::string& device_id,
                                     MediaStreamType type,
@@ -631,7 +636,7 @@ void MediaStreamManager::OpenDevice(MediaStreamRequester* requester,
                                              security_origin,
                                              MEDIA_OPEN_DEVICE,
                                              options,
-                                             rc);
+                                             sc);
 
   const std::string& label = AddRequest(request);
   // Post a task and handle the request asynchronously. The reason is that the
@@ -660,8 +665,8 @@ void MediaStreamManager::StopRemovedDevices(
   for (StreamDeviceInfoArray::const_iterator old_dev_it = old_devices.begin();
        old_dev_it != old_devices.end(); ++old_dev_it) {
     bool device_found = false;
-    for (StreamDeviceInfoArray::const_iterator new_dev_it = new_devices.begin();
-         new_dev_it != new_devices.end(); ++new_dev_it) {
+    StreamDeviceInfoArray::const_iterator new_dev_it = new_devices.begin();
+    for (; new_dev_it != new_devices.end(); ++new_dev_it) {
       if (old_dev_it->device.id == new_dev_it->device.id) {
         device_found = true;
         break;
@@ -685,7 +690,7 @@ void MediaStreamManager::StopRemovedDevice(const MediaStreamDevice& device) {
              request->devices.begin();
          device_it != request->devices.end(); ++device_it) {
       std::string source_id = content::GetHMACForMediaDeviceID(
-          request->resource_context,
+          request->salt_callback,
           request->security_origin,
           device.id);
       if (device_it->device.id == source_id &&
@@ -759,7 +764,7 @@ bool MediaStreamManager::GetRequestedDeviceCaptureId(
   // id.
   if (source_ids.size() == 1 &&
       !TranslateSourceIdToDeviceId(type,
-                                   request->resource_context,
+                                   request->salt_callback,
                                    request->security_origin,
                                    source_ids[0], device_id)) {
     LOG(WARNING) << "Invalid mandatory audio " << kMediaStreamSourceInfoId
@@ -776,7 +781,7 @@ bool MediaStreamManager::GetRequestedDeviceCaptureId(
     for (std::vector<std::string>::const_iterator it = source_ids.begin();
          it != source_ids.end(); ++it) {
       if (TranslateSourceIdToDeviceId(type,
-                                      request->resource_context,
+                                      request->salt_callback,
                                       request->security_origin,
                                       *it,
                                       device_id)) {
@@ -793,7 +798,7 @@ void MediaStreamManager::TranslateDeviceIdToSourceId(
   if (request->audio_type() == MEDIA_DEVICE_AUDIO_CAPTURE ||
       request->video_type() == MEDIA_DEVICE_VIDEO_CAPTURE) {
     device->id = content::GetHMACForMediaDeviceID(
-        request->resource_context,
+        request->salt_callback,
         request->security_origin,
         device->id);
   }
@@ -801,7 +806,7 @@ void MediaStreamManager::TranslateDeviceIdToSourceId(
 
 bool MediaStreamManager::TranslateSourceIdToDeviceId(
     MediaStreamType stream_type,
-    ResourceContext* rc,
+    const ResourceContext::SaltCallback& sc,
     const GURL& security_origin,
     const std::string& source_id,
     std::string* device_id) const {
@@ -822,7 +827,7 @@ bool MediaStreamManager::TranslateSourceIdToDeviceId(
   for (StreamDeviceInfoArray::const_iterator it = cache->devices.begin();
        it != cache->devices.end();
        ++it) {
-    if (content::DoesMediaDeviceIDMatchHMAC(rc, security_origin, source_id,
+    if (content::DoesMediaDeviceIDMatchHMAC(sc, security_origin, source_id,
                                             it->device.id)) {
       *device_id = it->device.id;
       return true;
@@ -1126,7 +1131,7 @@ bool MediaStreamManager::FindExistingRequestedDeviceInfo(
   DCHECK(existing_request_state);
 
   std::string source_id = content::GetHMACForMediaDeviceID(
-      new_request.resource_context,
+      new_request.salt_callback,
       new_request.security_origin,
       new_device_info.id);
 
diff --git a/content/browser/renderer_host/media/media_stream_manager.h b/content/browser/renderer_host/media/media_stream_manager.h
index 2c9fce4..590d241 100644
--- a/content/browser/renderer_host/media/media_stream_manager.h
+++ b/content/browser/renderer_host/media/media_stream_manager.h
@@ -35,6 +35,7 @@
 #include "content/common/content_export.h"
 #include "content/common/media/media_stream_options.h"
 #include "content/public/browser/media_request_state.h"
+#include "content/public/browser/resource_context.h"
 
 namespace base {
 class Thread;
@@ -51,7 +52,6 @@ class FakeMediaStreamUIProxy;
 class MediaStreamDeviceSettings;
 class MediaStreamRequester;
 class MediaStreamUIProxy;
-class ResourceContext;
 class VideoCaptureManager;
 
 // MediaStreamManager is used to generate and close new media devices, not to
@@ -97,7 +97,7 @@ class CONTENT_EXPORT MediaStreamManager
   void GenerateStream(MediaStreamRequester* requester,
                       int render_process_id,
                       int render_view_id,
-                      ResourceContext* rc,
+                      const ResourceContext::SaltCallback& sc,
                       int page_request_id,
                       const StreamOptions& components,
                       const GURL& security_origin);
@@ -126,12 +126,12 @@ class CONTENT_EXPORT MediaStreamManager
   // plug/unplug. The new device lists will be delivered via media observer to
   // MediaCaptureDevicesDispatcher.
   virtual std::string EnumerateDevices(MediaStreamRequester* requester,
-                               int render_process_id,
-                               int render_view_id,
-                               ResourceContext* rc,
-                               int page_request_id,
-                               MediaStreamType type,
-                               const GURL& security_origin);
+                                       int render_process_id,
+                                       int render_view_id,
+                                       const ResourceContext::SaltCallback& sc,
+                                       int page_request_id,
+                                       MediaStreamType type,
+                                       const GURL& security_origin);
 
   // Open a device identified by |device_id|.  |type| must be either
   // MEDIA_DEVICE_AUDIO_CAPTURE or MEDIA_DEVICE_VIDEO_CAPTURE.
@@ -139,7 +139,7 @@ class CONTENT_EXPORT MediaStreamManager
   void OpenDevice(MediaStreamRequester* requester,
                   int render_process_id,
                   int render_view_id,
-                  ResourceContext* rc,
+                  const ResourceContext::SaltCallback& sc,
                   int page_request_id,
                   const std::string& device_id,
                   MediaStreamType type,
@@ -309,7 +309,7 @@ class CONTENT_EXPORT MediaStreamManager
   // given |source_id|, false if nothing matched it.
   bool TranslateSourceIdToDeviceId(
       MediaStreamType stream_type,
-      ResourceContext* rc,
+      const ResourceContext::SaltCallback& rc,
       const GURL& security_origin,
       const std::string& source_id,
       std::string* device_id) const;
diff --git a/content/browser/renderer_host/media/video_capture_host_unittest.cc b/content/browser/renderer_host/media/video_capture_host_unittest.cc
index 551b0c2..c7ffcd5 100644
--- a/content/browser/renderer_host/media/video_capture_host_unittest.cc
+++ b/content/browser/renderer_host/media/video_capture_host_unittest.cc
@@ -300,7 +300,7 @@ class VideoCaptureHostTest : public testing::Test {
           &stream_requester_,
           render_process_id,
           render_view_id,
-          browser_context_.GetResourceContext(),
+          browser_context_.GetResourceContext()->GetMediaDeviceIDSalt(),
           page_request_id,
           MEDIA_DEVICE_VIDEO_CAPTURE,
           security_origin);
@@ -326,7 +326,7 @@ class VideoCaptureHostTest : public testing::Test {
           &stream_requester_,
           render_process_id,
           render_view_id,
-          browser_context_.GetResourceContext(),
+          browser_context_.GetResourceContext()->GetMediaDeviceIDSalt(),
           page_request_id,
           devices[0].device.id,
           MEDIA_DEVICE_VIDEO_CAPTURE,
diff --git a/content/browser/resource_context_impl.cc b/content/browser/resource_context_impl.cc
index 9561c8d..14115a4 100644
--- a/content/browser/resource_context_impl.cc
+++ b/content/browser/resource_context_impl.cc
@@ -37,6 +37,11 @@ class NonOwningZoomData : public base::SupportsUserData::Data {
   HostZoomMap* host_zoom_map_;
 };
 
+// Used by the default implementation of GetMediaDeviceIDSalt, below.
+std::string ReturnEmptySalt() {
+  return std::string();
+}
+
 }  // namespace
 
 
@@ -56,8 +61,8 @@ ResourceContext::~ResourceContext() {
   DetachUserDataThread();
 }
 
-std::string ResourceContext::GetMediaDeviceIDSalt() {
-  return std::string();
+ResourceContext::SaltCallback ResourceContext::GetMediaDeviceIDSalt() {
+  return base::Bind(&ReturnEmptySalt);
 }
 
 scoped_ptr<net::ClientCertStore> ResourceContext::CreateClientCertStore() {
diff --git a/content/public/browser/media_device_id.cc b/content/public/browser/media_device_id.cc
index 24709b2..65ac7e2 100644
--- a/content/public/browser/media_device_id.cc
+++ b/content/public/browser/media_device_id.cc
@@ -6,12 +6,11 @@
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
-#include "content/public/browser/resource_context.h"
 #include "crypto/hmac.h"
 
 namespace content {
 
-std::string GetHMACForMediaDeviceID(ResourceContext* rc,
+std::string GetHMACForMediaDeviceID(const ResourceContext::SaltCallback& sc,
                                     const GURL& security_origin,
                                     const std::string& raw_unique_id) {
   DCHECK(security_origin.is_valid());
@@ -19,21 +18,21 @@ std::string GetHMACForMediaDeviceID(ResourceContext* rc,
   crypto::HMAC hmac(crypto::HMAC::SHA256);
   const size_t digest_length = hmac.DigestLength();
   std::vector<uint8> digest(digest_length);
-  std::string salt = rc->GetMediaDeviceIDSalt();
+  std::string salt = sc.Run();
   bool result = hmac.Init(security_origin.spec()) &&
       hmac.Sign(raw_unique_id + salt, &digest[0], digest.size());
   DCHECK(result);
   return StringToLowerASCII(base::HexEncode(&digest[0], digest.size()));
 }
 
-bool DoesMediaDeviceIDMatchHMAC(ResourceContext* rc,
+bool DoesMediaDeviceIDMatchHMAC(const ResourceContext::SaltCallback& sc,
                                 const GURL& security_origin,
                                 const std::string& device_guid,
                                 const std::string& raw_unique_id) {
   DCHECK(security_origin.is_valid());
   DCHECK(!raw_unique_id.empty());
   std::string guid_from_raw_device_id =
-      GetHMACForMediaDeviceID(rc, security_origin, raw_unique_id);
+      GetHMACForMediaDeviceID(sc, security_origin, raw_unique_id);
   return guid_from_raw_device_id == device_guid;
 }
 
diff --git a/content/public/browser/media_device_id.h b/content/public/browser/media_device_id.h
index 50a3e0c..e14809c 100644
--- a/content/public/browser/media_device_id.h
+++ b/content/public/browser/media_device_id.h
@@ -13,23 +13,22 @@
 #include <string>
 
 #include "content/common/content_export.h"
+#include "content/public/browser/resource_context.h"
 #include "url/gurl.h"
 
 namespace content {
 
-class ResourceContext;
-
 // Generates a one-way hash of a device's unique ID usable by one
 // particular security origin.
 CONTENT_EXPORT std::string GetHMACForMediaDeviceID(
-    ResourceContext* rc,
+    const ResourceContext::SaltCallback& sc,
     const GURL& security_origin,
     const std::string& raw_unique_id);
 
 // Convenience method to check if |device_guid| is an HMAC of
 // |raw_device_id| for |security_origin|.
 CONTENT_EXPORT bool DoesMediaDeviceIDMatchHMAC(
-    ResourceContext* rc,
+    const ResourceContext::SaltCallback& sc,
     const GURL& security_origin,
     const std::string& device_guid,
     const std::string& raw_unique_id);
diff --git a/content/public/browser/resource_context.h b/content/public/browser/resource_context.h
index 1308d76..58eb298 100644
--- a/content/public/browser/resource_context.h
+++ b/content/public/browser/resource_context.h
@@ -68,11 +68,29 @@ class CONTENT_EXPORT ResourceContext : public base::SupportsUserData {
   // resource metadata.
   virtual bool AllowCameraAccess(const GURL& origin) = 0;
 
-  // Returns a random salt string that is used for creating media device IDs.
-  // The salt should be stored in the current user profile and should be reset
-  // if cookies are cleared. Returns an empty string per default.
-  // TODO(perkj): Make this method pure virtual when crbug/315022 is fixed.
-  virtual std::string GetMediaDeviceIDSalt();
+  // Returns a callback that can be invoked to get a random salt
+  // string that is used for creating media device IDs.  The salt
+  // should be stored in the current user profile and should be reset
+  // if cookies are cleared. The default is an empty string.
+  //
+  // It is safe to hold on to the callback returned and use it without
+  // regard to the lifetime of ResourceContext, although in general
+  // you should not use it long after the profile has been destroyed.
+  //
+  // TODO(joi): We don't think it should be unnecessary to use this
+  // after ResourceContext goes away. There is likely an underying bug
+  // in the lifetime of ProfileIOData vs. ResourceProcessHost, where
+  // sometimes ProfileIOData has gone away before RPH has finished
+  // being torn down (on the IO thread). The current interface that
+  // allows using the salt object after ResourceContext has gone away
+  // was put in place to fix http://crbug.com/341211 but I intend to
+  // try to figure out how the lifetime should be fixed properly. The
+  // original interface was just a method that returns a string.
+  //
+  // TODO(perkj): Make this method pure virtual when crbug/315022 is
+  // fixed.
+  typedef base::Callback<std::string()> SaltCallback;
+  virtual SaltCallback GetMediaDeviceIDSalt();
 };
 
 }  // namespace content
diff --git a/content/test/webrtc_audio_device_test.cc b/content/test/webrtc_audio_device_test.cc
index f414a82..1f30b68 100644
--- a/content/test/webrtc_audio_device_test.cc
+++ b/content/test/webrtc_audio_device_test.cc
@@ -174,10 +174,6 @@ class MockRTCResourceContext : public ResourceContext {
     return false;
   }
 
-  virtual std::string GetMediaDeviceIDSalt() OVERRIDE {
-    return "";
-  }
-
  private:
   net::URLRequestContext* test_request_context_;