AndroidOverlay implementation using Dialog.

content/public/browser/render_frame_host.h

Index: content/public/browser/render_frame_host.h
diff --git a/content/public/browser/render_frame_host.h b/content/public/browser/render_frame_host.h
index f7d7cb1303ef94bfd5222098383cf75c99742a40..3972e6fd5b70cb50c0bc6c56fc511aad7b041eb0 100644
--- a/content/public/browser/render_frame_host.h
+++ b/content/public/browser/render_frame_host.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/callback_forward.h"
+#include "base/unguessable_token.h"
 #include "build/build_config.h"
 #include "content/common/content_export.h"
 #include "content/public/common/console_message_level.h"
@@ -59,6 +60,12 @@ class CONTENT_EXPORT RenderFrameHost : public IPC::Listener,
   // Returns a RenderFrameHost given its accessibility tree ID.
   static RenderFrameHost* FromAXTreeID(int ax_tree_id);
 
+#if defined(OS_ANDROID)
+  // Returns a RenderFrameHost given its AndroidOverlay routing token.
+  static RenderFrameHost* FromOverlayRoutingToken(
+      const base::UnguessableToken& token);
+#endif
+
   ~RenderFrameHost() override {}
 
   // Returns the route id for this frame.
@@ -67,6 +74,16 @@ class CONTENT_EXPORT RenderFrameHost : public IPC::Listener,
   // Returns the accessibility tree ID for this RenderFrameHost.
   virtual int GetAXTreeID() = 0;
 
+#if defined(OS_ANDROID)
+  // Returns an unguessable token for this RFHI.  This provides a temporary way
+  // to identify a RenderFrameHost that's compatible with IPC.  Else, one needs
+  // to send pid + RoutingID, but one cannot send pid.  One can get it from the
+  // channel, but this makes it much harder to get wrong.
+  // Once media switches to mojo, we should be able to remove this in favor of
+  // sending a mojo overlay factory.
+  virtual const base::UnguessableToken& GetOverlayRoutingToken() = 0;

[boliu, 2017/03/30 22:42:02]

ditto about public

[liberato (no reviews please), 2017/04/04 17:49:28]

Done.

+#endif
+
   // Returns the SiteInstance grouping all RenderFrameHosts that have script
   // access to this RenderFrameHost, and must therefore live in the same
   // process.