Move more of ContentHandler handling into PackageManager.

content/browser/mojo/mojo_shell_context.cc

Index: content/browser/mojo/mojo_shell_context.cc
diff --git a/content/browser/mojo/mojo_shell_context.cc b/content/browser/mojo/mojo_shell_context.cc
index 2c94008b0b694fd954649656b998b69ab48de59b..db77c35f4e5985c85594eab894d91f5e95fae11b 100644
--- a/content/browser/mojo/mojo_shell_context.cc
+++ b/content/browser/mojo/mojo_shell_context.cc
@@ -160,7 +160,7 @@ MojoShellContext::MojoShellContext() {
   // Construct with an empty filepath since mojo: urls can't be registered now
   // the url scheme registry is locked.
   scoped_ptr<mojo::package_manager::PackageManagerImpl> package_manager(
-      new mojo::package_manager::PackageManagerImpl(base::FilePath()));
+      new mojo::package_manager::PackageManagerImpl(base::FilePath(), nullptr));

[yzshen1, 2015/09/23 16:53:46]

Passing null could crash in some cases (e.g., LocalFetcher is used in
HandleWithContentHandler). Although the code path might not be reached, I feel
that we need to either pass a valid task runner or document clearly under what
circumstances nullptr is acceptable.

[Ben Goodger (Google), 2015/09/23 18:24:20]

Good point. Currently nullptr is equivalent to not calling set_blocking_pool()
on ApplicationManager. The only client of ApplicationManager that calls this
method is Context. The other cases are tests, and in this instance content. This
code will have to change if it ever wants to load mojo apps using Local or
NetworkFetcher.

I've updated the documentation in package_manager_impl.h and
application_manager.h to reflect this.

   application_manager_.reset(
       new mojo::shell::ApplicationManager(package_manager.Pass()));