[chromecast] Obtain initial focus in webviews

  * Observes visibility of the aura window that contains the webview
    and adds a new OnVisible hook when the window is made visible.
  * Requests initial focus when visible.
  * Same OnVisible hook will be used to register IME observers in a
    forthcoming cl.

Bug: internal b/169848935, internal b/161811385
Test: manual on device and with wayland webview client
Change-Id: I37d0dad610f99398363c6b8f91579cb0a42853c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2487700
Commit-Queue: Ryan Daum <rdaum@chromium.org>
Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819648}

chromecast/browser/webview/web_content_controller.cc

@@ -31,6 +31,33 @@
 
 namespace chromecast {
 
+WebContentController::WebviewWindowVisibilityObserver::
+    WebviewWindowVisibilityObserver(aura::Window* window,
+                                    WebContentController* controller)
+    : window_(window), controller_(controller) {
+  DCHECK(window_);
+  DCHECK(controller_);
+  window_->AddObserver(this);
+}
+
+void WebContentController::WebviewWindowVisibilityObserver::
+    OnWindowVisibilityChanged(aura::Window* window, bool visible) {
+  if (window == window_ && visible && window->CanFocus())
+    controller_->OnVisible(window);
+}
+
+void WebContentController::WebviewWindowVisibilityObserver::OnWindowDestroyed(
+    aura::Window* window) {
+  if (window == window_)
+    window_ = nullptr;
+}
+
+WebContentController::WebviewWindowVisibilityObserver::
+    ~WebviewWindowVisibilityObserver() {
+  if (window_)
+    window_->RemoveObserver(this);
+}
+
 WebContentController::WebContentController(Client* client) : client_(client) {
   js_channels_ = std::make_unique<WebContentJsChannels>(client_);
   JsClientInstance::AddObserver(this);
@@ -149,6 +176,11 @@ void WebContentController::ProcessRequest(
 }
 
 void WebContentController::AttachTo(aura::Window* window, int window_id) {
+  // Register our observer on the window so we can act later once it
+  // becomes visible.
+  window_visibility_observer_ =
+      std::make_unique<WebviewWindowVisibilityObserver>(window, this);
+
   content::WebContents* contents = GetWebContents();
   auto* contents_window = contents->GetNativeView();
   contents_window->set_id(window_id);
@@ -170,6 +202,11 @@ void WebContentController::AttachTo(aura::Window* window, int window_id) {
   HandleResize(contents_window->bounds().size());
 }
 
+void WebContentController::OnVisible(aura::Window* window) {
+  // Acquire initial focus.
+  GetWebContents()->SetInitialFocus();
+}
+
 void WebContentController::ProcessInputEvent(const webview::InputEvent& ev) {
   content::WebContents* contents = GetWebContents();
   DCHECK(contents);

chromecast/browser/webview/web_content_controller.h

@@ -63,6 +63,9 @@ class WebContentController
   // Attach this web contents to an aura window as a child.
   void AttachTo(aura::Window* window, int window_id);
 
+  // Invoked when the aura window becomes visible and is fully initialized.
+  void OnVisible(aura::Window* window);
+
  protected:
   // content::WebContentsObserver
   void RenderFrameCreated(content::RenderFrameHost* render_frame_host) override;
@@ -139,6 +142,30 @@ class WebContentController
   std::set<content::RenderFrameHost*> current_render_frame_set_;
   std::set<content::RenderWidgetHost*> current_render_widget_set_;
 
+  // Observes the aura window and calls back to the controller for visibility
+  // events.
+  class WebviewWindowVisibilityObserver : public aura::WindowObserver {
+   public:
+    explicit WebviewWindowVisibilityObserver(aura::Window* window,
+                                             WebContentController* controller);
+    ~WebviewWindowVisibilityObserver() override;
+
+    WebviewWindowVisibilityObserver(const WebviewWindowVisibilityObserver&) =
+        delete;
+    WebviewWindowVisibilityObserver& operator=(
+        const WebviewWindowVisibilityObserver&) = delete;
+
+   private:
+    // aura::WindowObserver
+    void OnWindowVisibilityChanged(aura::Window* window, bool visible) override;
+    void OnWindowDestroyed(aura::Window* window) override;
+
+    aura::Window* window_;
+    WebContentController* controller_;
+  };
+
+  std::unique_ptr<WebviewWindowVisibilityObserver> window_visibility_observer_;
+
   base::WeakPtrFactory<WebContentController> weak_ptr_factory_{this};
 
   DISALLOW_COPY_AND_ASSIGN(WebContentController);