[mojo-edk] Expose notification source to MojoWatch callbacks

mojo/edk/system/request_context.h

Index: mojo/edk/system/request_context.h
diff --git a/mojo/edk/system/request_context.h b/mojo/edk/system/request_context.h
index 56b849870e33ba07048d5f450e911880be51b045..558d163748948ca1d2a91d4b713d5ffdde145e89 100644
--- a/mojo/edk/system/request_context.h
+++ b/mojo/edk/system/request_context.h
@@ -8,6 +8,7 @@
 #include "base/containers/stack_container.h"
 #include "base/macros.h"
 #include "mojo/edk/system/handle_signals_state.h"
+#include "mojo/edk/system/system_impl_export.h"
 #include "mojo/edk/system/watcher.h"
 
 namespace base {
@@ -27,14 +28,22 @@ namespace edk {
 // for any reason. Therefore it is important to always use
 // |RequestContext::current()| rather than referring to any local instance
 // directly.
-class RequestContext {
+class MOJO_SYSTEM_IMPL_EXPORT RequestContext {
  public:
-  RequestContext();
+  // Identifies the source of the current stack frame's RequestContext.
+  enum class Source {
+    LOCAL_API_CALL,
+    EXTERNAL_PROCESS,
+  };
+
+  explicit RequestContext(Source source);

[Anand Mistry (off Chromium), 2016/03/16 23:04:14]

If local is the default and "external process" is the exceptional case, have a
default constructor that uses local. It avoids all the dispatcher changes. If
you do, make sure you add a comment that local is the default.

And we can use delegated constructors now, so this should be trivial.

[Ken Rockot(use gerrit already), 2016/03/17 00:15:34]

Done

   ~RequestContext();
 
   // Returns the current thread-local RequestContext.
   static RequestContext* current();
 
+  Source source() const { return source_; }
+
   // Adds a finalizer to this RequestContext corresponding to a watch callback
   // which should be triggered in response to some handle state change. If
   // the Watcher hasn't been cancelled by the time this RequestContext is
@@ -48,6 +57,7 @@ class RequestContext {
   void AddWatchCancelFinalizer(scoped_refptr<Watcher> watcher);
 
  private:
+  //

[Anand Mistry (off Chromium), 2016/03/16 23:04:14]

nit: blank comment line.

[Ken Rockot(use gerrit already), 2016/03/17 00:15:34]

done

   // Is this request context the current one?
   bool IsCurrent() const;
 
@@ -74,6 +84,12 @@ class RequestContext {
   using WatchCancelFinalizerList =
       base::StackVector<scoped_refptr<Watcher>, kStaticWatchFinalizersCapacity>;
 
+  Source source_;
+
+  // A nested RequestContext may override the Source of the thread-local
+  // RequestContext for the duration of the nested context's lifetime.
+  Source outer_source_;
+
   WatchNotifyFinalizerList watch_notify_finalizers_;
   WatchCancelFinalizerList watch_cancel_finalizers_;