[CrOS MultiDevice] Clean up MojoWebDialogUI.

In https://chromium-review.googlesource.com/c/chromium/src/+/991497,
calamity@ refactored this class such that it no longer derived from a
template base class.

However, that CL did not actually remove the template type from
MojoWebDialogUI, so this CL finishes that effort up. Additionally, since
the class is no longer a template class, I moved implementations of
functions from the .h file to the .cc file.

Bug: 824568
Change-Id: Ibabd6d4a282069f246821314ec71b4a5ac1c7bd4
Reviewed-on: https://chromium-review.googlesource.com/1138980Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575493}

ui/web_dialogs/web_dialog_ui.cc

@@ -120,4 +120,15 @@ void WebDialogUI::RenderFrameCreated(RenderFrameHost* render_frame_host) {
   HandleRenderFrameCreated(render_frame_host);
 }
 
+MojoWebDialogUI::MojoWebDialogUI(content::WebUI* web_ui)
+    : WebDialogUIBase(web_ui), MojoWebUIController(web_ui) {}
+
+MojoWebDialogUI::~MojoWebDialogUI() = default;
+
+void MojoWebDialogUI::RenderFrameCreated(
+    content::RenderFrameHost* render_frame_host) {
+  content::WebUIController::RenderFrameCreated(render_frame_host);
+  HandleRenderFrameCreated(render_frame_host);
+}
+
 }  // namespace ui

ui/web_dialogs/web_dialog_ui.h

@@ -83,23 +83,17 @@ class WEB_DIALOGS_EXPORT WebDialogUI : public WebDialogUIBase,
 
 // Displays file URL contents inside a modal web dialog while also enabling
 // Mojo calls to be made from within the dialog.
-template <typename Interface>
 class WEB_DIALOGS_EXPORT MojoWebDialogUI : public WebDialogUIBase,
                                            public MojoWebUIController {
  public:
   // When created, the delegate should already be set as user data on the
   // WebContents.
-  explicit MojoWebDialogUI(content::WebUI* web_ui)
-      : WebDialogUIBase(web_ui), MojoWebUIController(web_ui) {}
-  ~MojoWebDialogUI() override {}
+  explicit MojoWebDialogUI(content::WebUI* web_ui);
+  ~MojoWebDialogUI() override;
 
  private:
   // content::WebUIController:
-  void RenderFrameCreated(
-      content::RenderFrameHost* render_frame_host) override {
-    content::WebUIController::RenderFrameCreated(render_frame_host);
-    HandleRenderFrameCreated(render_frame_host);
-  }
+  void RenderFrameCreated(content::RenderFrameHost* render_frame_host) override;
 
   DISALLOW_COPY_AND_ASSIGN(MojoWebDialogUI);
 };