[Chromecast] Introduce CastWebContents

Pulls common logic from CastWebView implementations into a shared base
class. The main intent of this new class is to wrap WebContents and
provide a simplified API for consumers in Cast.

Merge-With: eureka-internal/206097

Bug: internal b/77879457
Test: CQ
Change-Id: I46c952613e0dcf3631941a27160b34390386ad30
Reviewed-on: https://chromium-review.googlesource.com/c/1263420
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Sean Topping <seantopping@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602851}

chromecast/browser/BUILD.gn

@@ -51,6 +51,8 @@ cast_source_set("browser") {
     "cast_quota_permission_context.h",
     "cast_resource_dispatcher_host_delegate.cc",
     "cast_resource_dispatcher_host_delegate.h",
+    "cast_web_contents_impl.cc",
+    "cast_web_contents_impl.h",
     "cast_web_contents_manager.cc",
     "cast_web_contents_manager.h",
     "cast_web_view_default.cc",
@@ -334,6 +336,7 @@ cast_source_set("public") {
   sources = [
     "cast_content_window.cc",
     "cast_content_window.h",
+    "cast_web_contents.h",
     "cast_web_view.cc",
     "cast_web_view.h",
   ]

chromecast/browser/cast_extension_host.cc

@@ -60,12 +60,6 @@ void CastExtensionHost::LoadInitialURL() {
   extensions::ExtensionHost::LoadInitialURL();
 }
 
-void CastExtensionHost::LoadingStateChanged(content::WebContents* source,
-                                            bool to_different_document) {
-  extensions::ExtensionHost::LoadingStateChanged(source, to_different_document);
-  delegate_->OnLoadingStateChanged(source->IsLoading());
-}
-
 void CastExtensionHost::ActivateContents(content::WebContents* contents) {
   DCHECK_EQ(contents, host_contents());
   contents->GetRenderViewHost()->GetWidget()->Focus();

chromecast/browser/cast_extension_host.h

@@ -43,8 +43,6 @@ class CastExtensionHost : public extensions::ExtensionHost,
   void ActivateContents(content::WebContents* contents) override;
   void DidStartNavigation(
       content::NavigationHandle* navigation_handle) override;
-  void LoadingStateChanged(content::WebContents* source,
-                           bool to_different_document) override;
   bool DidAddMessageToConsole(content::WebContents* source,
                               int32_t level,
                               const base::string16& message,

chromecast/browser/cast_web_contents.h

@@ -0,0 +1,83 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMECAST_BROWSER_CAST_WEB_CONTENTS_H_
+#define CHROMECAST_BROWSER_CAST_WEB_CONTENTS_H_
+
+#include "url/gurl.h"
+
+namespace content {
+class WebContents;
+}  // namespace content
+
+namespace chromecast {
+
+// Simplified WebContents wrapper class for Cast platforms.
+class CastWebContents {
+ public:
+  class Delegate {
+   public:
+    // Advertises page state for the CastWebContents.
+    // Use CastWebContents::page_state() to get the new state.
+    virtual void OnPageStateChanged(CastWebContents* cast_web_contents) = 0;
+
+    // Called when the page has stopped. e.g.: A 404 occurred when loading the
+    // page or if the render process for the main frame crashes. |error_code|
+    // will return a net::Error describing the failure, or net::OK if the page
+    // closed naturally.
+    //
+    // After this method, the page state will be one of the following:
+    // CLOSED: Page was closed as expected and the WebContents exists.
+    // DESTROYED: Page was closed due to deletion of WebContents. The
+    //     CastWebContents instance is no longer usable and should be deleted.
+    // ERROR: Page is in an error state. It should be reloaded or deleted.
+    virtual void OnPageStopped(CastWebContents* cast_web_contents,
+                               int error_code) = 0;
+
+   protected:
+    virtual ~Delegate() {}
+  };
+
+  // Page state for the main frame.
+  enum class PageState {
+    IDLE,       // Main frame has not started yet.
+    LOADING,    // Main frame is loading resources.
+    LOADED,     // Main frame is loaded, but sub-frames may still be loading.
+    CLOSED,     // Page is closed and should be cleaned up.
+    DESTROYED,  // The WebContents is destroyed and can no longer be used.
+    ERROR,      // Main frame is in an error state.
+  };
+
+  CastWebContents() = default;
+  virtual ~CastWebContents() = default;
+
+  virtual content::WebContents* web_contents() const = 0;
+  virtual PageState page_state() const = 0;
+
+  // Navigates the underlying WebContents to |url|. Delegate will be notified of
+  // page progression events via OnPageStateChanged().
+  virtual void LoadUrl(const GURL& url) = 0;
+
+  // Initiate closure of the page. This invokes the appropriate unload handlers.
+  // Eventually the delegate will be notified with OnPageStopped().
+  virtual void ClosePage() = 0;
+
+  // Stop the page immediately. This will automatically invoke
+  // Delegate::OnPageStopped(error_code), allowing the delegate to delete or
+  // reload the page without waiting for page teardown, which may be handled
+  // independently.
+  virtual void Stop(int error_code) = 0;
+
+  // Set the delegate. SetDelegate(nullptr) can be used to stop notifications.
+  virtual void SetDelegate(Delegate* delegate) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CastWebContents);
+};
+
+std::ostream& operator<<(std::ostream& os, CastWebContents::PageState state);
+
+}  // namespace chromecast
+
+#endif  // CHROMECAST_BROWSER_CAST_WEB_CONTENTS_H_