Adding MimeHandlerView.

This GuestView type would be used to render out of process pdf through extension.
This introduces BrowserPluginDelegate in content/renderer,
because we need a way to create a MimeHandlerView guest (extensions/ concept)
from BrowserPlugin (content/ concept).

MimeHandlerView is behind --enable-mime-handler-view flag.

BUG=303491
Test=Apply http://crrev.com/392813003/ on top of this CL,
Launch chrome with --out-of-process-pdf flag and --enable-mime-handler-view flag
Navigate to a PDF
Check PDF is served using BrowserPlugin, probably easier to see process associated with the BrowserPlugin from Chrome's task manager.

Review URL: https://codereview.chromium.org/376033002

Cr-Commit-Position: refs/heads/master@{#293613}

1 files changed, 11 insertions, 0 deletions

diff --git a/extensions/common/extension_messages.h b/extensions/common/extension_messages.h
index 6feae8c..8b090ca 100644
--- a/extensions/common/extension_messages.h
+++ b/extensions/common/extension_messages.h
@@ -512,6 +512,10 @@ IPC_MESSAGE_CONTROL1(ExtensionMsg_WatchPages,
 IPC_MESSAGE_CONTROL1(ExtensionMsg_TransferBlobs,
                      std::vector<std::string> /* blob_uuids */)
 
+// The ACK for ExtensionHostMsg_CreateMimeHandlerViewGuest.
+IPC_MESSAGE_CONTROL1(ExtensionMsg_CreateMimeHandlerViewGuestACK,
+                     int /* element_instance_id */)
+
 // Messages sent from the renderer to the browser.
 
 // A renderer sends this message when an extension process starts an API
@@ -733,3 +737,10 @@ IPC_MESSAGE_CONTROL4(ExtensionHostMsg_AttachGuest,
                      int /* element_instance_id */,
                      int /* guest_instance_id */,
                      base::DictionaryValue /* attach_params */)
+
+// Tells the browser to create a mime handler guest view for a plugin.
+IPC_MESSAGE_CONTROL4(ExtensionHostMsg_CreateMimeHandlerViewGuest,
+                     int /* render_frame_id */,
+                     std::string /* embedder_url */,
+                     std::string /* mime_type */,
+                     int /* element_instance_id */)