        ]
        #TODO(jrummell) Mac: 'DYLIB_INSTALL_NAME_BASE': '@loader_path',
      } else if (is_posix && !is_mac) {
+diff --git a/third_party/widevine/cdm/stub/manifest.json b/third_party/widevine/cdm/stub/manifest.json
+index d466ccd1e02ed8c158fda545fe2175c135018da5..16ae2a357b21de66b1558939f9333b3c22e9cff2 100644
+--- a/third_party/widevine/cdm/stub/manifest.json
++++ b/third_party/widevine/cdm/stub/manifest.json
+@@ -24,6 +24,11 @@
+       "os": "mac",
+       "arch": "x64",
+       "sub_package_path": "_platform_specific/mac_x64/"
++    },
++    {
++      "os": "linux",
++      "arch": "x64",
++      "sub_package_path": "_platform_specific/linux_x64/"
+     }
+   ]
+ }

   }
 
   bool ShouldSelectReplacement() const {
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
index 76a36536f92ca5cc361e35cb8e27de1bbcc88327..004e678da6e383cfb97fbd7022d9faca35ec6581 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 #endif
 
 // On macOS this value is adjusted in `UpdateScrollbarTheme()`,
diff --git a/extensions/browser/api/messaging/message_service.cc b/extensions/browser/api/messaging/message_service.cc
index 8b84570b413d6bd94dc20163a900dbb813023c5d..9201884dab7030724e695763f57baf44ac3c6513 100644
--- a/extensions/browser/api/messaging/message_service.cc
+++ b/extensions/browser/api/messaging/message_service.cc
@@ -124,6 +124,11 @@ namespace {
 static content::RenderProcessHost* GetExtensionProcess(
     BrowserContext* context,
     const std::string& extension_id) {
+  auto original = ExtensionsBrowserClient::Get()->GetOriginalContext(context);
+  // Always use the original context for non-private child contexts
+  if (!context->IsOffTheRecord()) {
+    context = original;
+  }
   scoped_refptr<SiteInstance> site_instance =
       ProcessManager::Get(context)->GetSiteInstanceForURL(
           Extension::GetBaseURLFromExtensionId(extension_id));
diff --git a/extensions/browser/guest_view/extensions_guest_view_manager_delegate.cc b/extensions/browser/guest_view/extensions_guest_view_manager_delegate.cc
index 0199c3356074ff8d88682386cb1aa512e59a4c1f..0a04887e6ce97d5e6037bb34c85babab86287dba 100644
--- a/extensions/browser/guest_view/extensions_guest_view_manager_delegate.cc
