Add service registration for apps APIs implemented as mojo services.

extensions/browser/service_registration_manager.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "extensions/browser/service_registration_manager.h"
+
+#include "base/command_line.h"
+#include "base/lazy_instance.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/site_instance.h"
+#include "device/serial/serial_service_impl.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/browser/process_map.h"
+#include "extensions/common/constants.h"
+#include "extensions/common/extension_api.h"
+#include "extensions/common/switches.h"
+
+namespace extensions {
+namespace {
+
+base::LazyInstance<ServiceRegistrationManager> g_lazy_instance =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+ServiceRegistrationManager::ServiceRegistrationManager() {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableMojoSerialService)) {
+    AddServiceFactory(
+        "serial",
+        base::Bind(device::SerialServiceImpl::CreateOnMessageLoop,
+                   content::BrowserThread::GetMessageLoopProxyForThread(
+                       content::BrowserThread::FILE),
+                   content::BrowserThread::GetMessageLoopProxyForThread(
+                       content::BrowserThread::IO)));
+  }
+}
+
+ServiceRegistrationManager::~ServiceRegistrationManager() {
+}
+
+ServiceRegistrationManager* ServiceRegistrationManager::GetSharedInstance() {
+  return g_lazy_instance.Pointer();
+}
+
+void ServiceRegistrationManager::AddToRenderFrame(
+    content::RenderFrameHost* render_frame_host) {
+  content::BrowserContext* context =
+      render_frame_host->GetProcess()->GetBrowserContext();
+  content::SiteInstance* site_instance = render_frame_host->GetSiteInstance();
+  GURL site_url = site_instance->GetSiteURL();
+  ExtensionRegistry* registry = ExtensionRegistry::Get(context);
+
+  // TODO(sammc): Handle content scripts and web pages that have access to some
+  // extension APIs.
+  if (!site_url.SchemeIs(kExtensionScheme)) {
+    return;
+  }
+
+  const Extension* extension =
+      registry->enabled_extensions().GetByID(site_url.host());
+  DCHECK(extension);
+
+  Feature::Context context_type =
+      ProcessMap::Get(context)->GetMostLikelyContextType(
+          extension, render_frame_host->GetProcess()->GetID());

[raymes, 2014/10/15 20:22:49]

I don't really understand the details of this. Is there something we have to be
worried about here or will this always get the right context type?

[Sam McNally, 2014/10/20 00:22:07]

I don't think this will make anything worse than it currently is.

+kalman for real answers.

[raymes, 2014/10/20 02:12:55]

Thanks. kalman@ it would be great if you could review the changes in this file,
I'm less familiar with this stuff.

[not at google - send to devlin, 2014/10/20 18:28:31]

Short answer: yes.

Long answer: it's complicated and the method has a long explanation of why:

https://code.google.com/p/chromium/codesearch#chromium/src/extensions/browser...

+  for (const auto& factory : factories_) {
+    // Note: The RenderFrame has not yet navigated to a particular URL so we
+    // pass |site_url| as the URL for permission checking. This is sufficient

[raymes, 2014/10/15 20:22:50]

What other URL would we pass? I'm not quite sure I understand what the general
case would look like.

[Sam McNally, 2014/10/20 00:22:07]

The actual URL loaded by the frame. This might matter for
https://developer.chrome.com/apps/manifest/externally_connectable for example.

[raymes, 2014/10/20 02:12:55]

Maybe we can name "site_url"->"extension_url" for now and possibly remove this
comment. Later when we revisit the general case it will be clearer that we might
need to use a different URL.

[Sam McNally, 2014/10/20 07:28:19]

Done.

+    // for now because we only reach this point for URLs with a scheme of
+    // chrome-extension. This will need to change once we begin supporting
+    // arbitrary sites URLs that may have access to extensions APIs.
+    if (ExtensionAPI::GetSharedInstance()
+            ->IsAvailable(factory.first, extension, context_type, site_url)

[raymes, 2014/10/15 20:22:50]

Is it possible for the security context to of a RenderFrame to change? Could it
be navigated to a different URL and we decide we no longer want to grant
permissions there? My guess is that the answer is no, but just wanted to check
:)

[Sam McNally, 2014/10/20 00:22:07]

As far as I can tell from the documentation the answer is no.

+            .is_available()) {
+      factory.second->Register(render_frame_host->GetServiceRegistry());
+    }
+  }
+}
+
+}  // namespace extensions