Allow app_shell embedders to override extensions client interfaces

This includes ExtensionsClient and ExtensionsBrowserClient.

BUG=none
TEST=app_shell_unittests

Review URL: https://codereview.chromium.org/717233003

Cr-Commit-Position: refs/heads/master@{#304946}

2 files changed, 12 insertions, 3 deletions

diff --git a/extensions/shell/renderer/shell_content_renderer_client.cc b/extensions/shell/renderer/shell_content_renderer_client.cc
index 216eac6..a56c009 100644
--- a/extensions/shell/renderer/shell_content_renderer_client.cc
+++ b/extensions/shell/renderer/shell_content_renderer_client.cc
@@ -79,7 +79,7 @@ ShellContentRendererClient::~ShellContentRendererClient() {
 void ShellContentRendererClient::RenderThreadStarted() {
   RenderThread* thread = RenderThread::Get();
 
-  extensions_client_.reset(new ShellExtensionsClient);
+  extensions_client_.reset(CreateExtensionsClient());
   ExtensionsClient::Set(extensions_client_.get());
 
   extensions_renderer_client_.reset(new ShellExtensionsRendererClient);
@@ -189,4 +189,8 @@ ShellContentRendererClient::CreateBrowserPluginDelegate(
   }
 }
 
+ExtensionsClient* ShellContentRendererClient::CreateExtensionsClient() {
+  return new ShellExtensionsClient;
+}
+
 }  // namespace extensions
diff --git a/extensions/shell/renderer/shell_content_renderer_client.h b/extensions/shell/renderer/shell_content_renderer_client.h
index 6f62398..b86fa0e 100644
--- a/extensions/shell/renderer/shell_content_renderer_client.h
+++ b/extensions/shell/renderer/shell_content_renderer_client.h
@@ -14,7 +14,7 @@ namespace extensions {
 
 class Dispatcher;
 class DispatcherDelegate;
-class ShellExtensionsClient;
+class ExtensionsClient;
 class ShellExtensionsRendererClient;
 class ShellRendererMainDelegate;
 
@@ -52,8 +52,13 @@ class ShellContentRendererClient : public content::ContentRendererClient {
       const std::string& mime_type,
       const GURL& original_url) override;
 
+ protected:
+  // app_shell embedders may need custom extensions client interfaces.
+  // This class takes ownership of the returned object.
+  virtual ExtensionsClient* CreateExtensionsClient();
+
  private:
-  scoped_ptr<ShellExtensionsClient> extensions_client_;
+  scoped_ptr<ExtensionsClient> extensions_client_;
   scoped_ptr<ShellExtensionsRendererClient> extensions_renderer_client_;
   scoped_ptr<DispatcherDelegate> extension_dispatcher_delegate_;
   scoped_ptr<Dispatcher> extension_dispatcher_;