Simplify resolution of mojo: URLs.

shell/context.h

Index: shell/context.h
diff --git a/shell/context.h b/shell/context.h
index b20b3fa85e6d18dcacfffc0f346b934f2cda712d..74abb6297a78789892751b2855c3289f6caadcdb 100644
--- a/shell/context.h
+++ b/shell/context.h
@@ -25,6 +25,9 @@ class Context : ApplicationManager::Delegate {
   Context();
   ~Context() override;
 
+  void SetShellFileRoot(const base::FilePath& path);

[Aaron Boodman, 2015/01/27 00:37:13]

Maybe a better name would be: SetMojoURLRoot?

[Nick Bray (chromium), 2015/01/27 01:44:35]

I'll comment this, but the fact it is the _file_ root is quite important.  (It's
used to resolving things installed along with mojo_shell.)

+  GURL ResolveShellFileURL(const std::string& path);

[Aaron Boodman, 2015/01/27 00:37:13]

These two methods need comments.

[Nick Bray (chromium), 2015/01/27 01:44:35]

Done.  <troll>But you could say that's against the style of this particular
file.</troll>

[Aaron Boodman, 2015/01/27 07:29:54]

True, but the reason I brought this up in particular was that it wasn't at all
clear to me what a "shell file URL" was, whereas the other members of this class
are more self-explanatory, at least to me.

[Nick Bray (chromium), 2015/01/27 16:36:25]

More comments are always better, particularly when a reviewer asks for
clarification.  Pure trolling on my part.

+
   static void EnsureEmbedderIsInitialized();
   bool Init();
 
@@ -50,6 +53,7 @@ class Context : ApplicationManager::Delegate {
   scoped_ptr<ExternalApplicationListener> listener_;
   ApplicationManager application_manager_;
   MojoURLResolver mojo_url_resolver_;
+  GURL shell_file_root_;
 
   DISALLOW_COPY_AND_ASSIGN(Context);
 };