[filesapp] Add SWA UI class to SWA page handler mojo pipe constructor

Mojo requests from the SWA WebContents appear on the receiving SWA page
handler mojo endpoint for servicing - that servicing will be handled by
the SWA UI class or its delegate.

Add the SWA UI class to the page handler mojo pipe constructor. Mention
it is the owning |this| since the page handler pipe is both created and
owned by the SWA UI class.

Bug: 1113981
Change-Id: Ic32e748df303cbaf26b82fe15d39c8b02cee92c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2580980Reviewed-by: Alex Danilo <adanilo@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835086}

chromeos/components/file_manager/file_manager_page_handler.cc

@@ -4,16 +4,20 @@
 
 #include "chromeos/components/file_manager/file_manager_page_handler.h"
 
-#include "base/bind.h"
+#include "chromeos/components/file_manager/file_manager_ui.h"
 
 namespace chromeos {
 namespace file_manager {
 
 FileManagerPageHandler::FileManagerPageHandler(
+    FileManagerUI* file_manager_ui,
     mojo::PendingReceiver<mojom::PageHandler> pending_receiver,
     mojo::PendingRemote<mojom::Page> pending_page)
-    : receiver_{this, std::move(pending_receiver)},
-      page_{std::move(pending_page)} {}
+    : file_manager_ui_(file_manager_ui),
+      receiver_(this, std::move(pending_receiver)),
+      page_(std::move(pending_page)) {
+  DCHECK(file_manager_ui_);
+}
 
 FileManagerPageHandler::~FileManagerPageHandler() = default;
 

chromeos/components/file_manager/file_manager_page_handler.h

@@ -16,10 +16,13 @@
 namespace chromeos {
 namespace file_manager {
 
+class FileManagerUI;
+
 // Class backing the page's functionality.
 class FileManagerPageHandler : public mojom::PageHandler {
  public:
   FileManagerPageHandler(
+      FileManagerUI* file_manager_ui,
       mojo::PendingReceiver<mojom::PageHandler> pending_receiver,
       mojo::PendingRemote<mojom::Page> pending_page);
   ~FileManagerPageHandler() override;
@@ -28,6 +31,7 @@ class FileManagerPageHandler : public mojom::PageHandler {
   FileManagerPageHandler& operator=(const FileManagerPageHandler&) = delete;
 
  private:
+  FileManagerUI* file_manager_ui_;  // Owns |this|.
   mojo::Receiver<mojom::PageHandler> receiver_;
   mojo::Remote<mojom::Page> page_;
 };

chromeos/components/file_manager/file_manager_ui.cc

@@ -69,7 +69,7 @@ void FileManagerUI::CreatePageHandler(
   DCHECK(pending_page.is_valid());
 
   page_handler_ = std::make_unique<FileManagerPageHandler>(
-      std::move(pending_page_handler), std::move(pending_page));
+      this, std::move(pending_page_handler), std::move(pending_page));
 }
 
 WEB_UI_CONTROLLER_TYPE_IMPL(FileManagerUI)