[chromecast] Enable element focus for WebContentController

Focus did not work due to two distinct problems, both of which caused
page-level focus to be absent, which in turn meant that blink-level
focus was suppressed.

- The aura::Window on which focus was attempted does not have an
  OnWindowFocused observer. This change focuses the Window that does.

- Wayland app's aura::Windows are not visible. This change adds a check
  for an ancestor that is an exo window.

Bug: b/156123509
Test: manual on device
Change-Id: Ib4e8a5101bbc28d2b7a0448aff8142c8cffa2a76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2274201Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Reviewed-by: Albert Chaulk <achaulk@chromium.org>
Commit-Queue: Kevin Schoedel <kpschoedel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#786469}

chromecast/browser/webview/web_content_controller.cc

@@ -12,6 +12,7 @@
 #include "chromecast/browser/cast_web_contents.h"
 #include "chromecast/browser/webview/proto/webview.pb.h"
 #include "chromecast/browser/webview/webview_navigation_throttle.h"
+#include "chromecast/graphics/cast_focus_client_aura.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browsing_data_remover.h"
 #include "content/public/browser/navigation_handle.h"
@@ -180,14 +181,23 @@ void WebContentController::AttachTo(aura::Window* window, int window_id) {
 void WebContentController::ProcessInputEvent(const webview::InputEvent& ev) {
   content::WebContents* contents = GetWebContents();
   DCHECK(contents);
-  DCHECK(contents->GetNativeView());
-  if (!contents->GetNativeView()->CanFocus())
-    return;
-  // Ensure this web contents has focus before sending it input.
-  if (!contents->GetNativeView()->HasFocus())
-    contents->GetNativeView()->Focus();
 
+  // Ensure this web contents has focus before sending it input.
+  // Focus at this level is necessary, or else Blink will ignore
+  // attempts to focus any elements in the contents.
+  //
+  // Via b/156123509: The aura::Window given by |contents->GetNativeView()|
+  // is not suitable for this purpose, because it has no OnWindowFocused
+  // observer. The |window| used here is the same one whose |delegate|
+  // is the EventHandler for this input event.
   content::RenderWidgetHostView* rwhv = contents->GetRenderWidgetHostView();
+  aura::Window* window = rwhv->GetNativeView();
+  DCHECK(window == contents->GetContentNativeView());
+  if (!window->CanFocus())
+    return;
+  if (!window->HasFocus())
+    window->Focus();
+
   ui::EventHandler* handler = rwhv->GetNativeView()->delegate();
   ui::EventType type = static_cast<ui::EventType>(ev.event_type());
   switch (type) {

chromecast/graphics/BUILD.gn

@@ -105,7 +105,10 @@ cast_source_set("graphics") {
   }
 
   if (use_ozone) {
-    deps += [ "//ui/ozone" ]
+    deps += [
+      "//components/exo",
+      "//ui/ozone",
+    ]
   }
 }
 

chromecast/graphics/DEPS

 include_rules = [
   "+chromecast/ui",
+  "+components/exo",
   "+components/viz/common/frame_sinks",
   "+ui/aura",
   "+ui/base",

chromecast/graphics/cast_focus_client_aura.cc

@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #include "base/stl_util.h"
+#include "components/exo/surface.h"
 #include "ui/aura/window.h"
 
 #define LOG_WINDOW_INFO(top_level, window)                              \
@@ -13,6 +14,19 @@
                 << "', window: " << (window)->id() << ": '"             \
                 << (window)->GetName() << "'"
 
+namespace {
+
+bool IsVisibleExoWindow(aura::Window* window) {
+  for (aura::Window* w = window; w; w = w->parent()) {
+    if (w->GetProperty(exo::kClientSurfaceIdKey) && w->IsVisible()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+}  // namespace
+
 namespace chromecast {
 
 CastFocusClientAura::CastFocusClientAura() : focused_window_(nullptr) {}
@@ -193,7 +207,10 @@ aura::Window* CastFocusClientAura::GetWindowToFocus() {
   aura::Window* next = nullptr;
   aura::Window* next_top_level = nullptr;
   for (aura::Window* window : focusable_windows_) {
-    if (!window->CanFocus() || !window->IsVisible()) {
+    if (!window->CanFocus()) {
+      continue;
+    }
+    if (!window->IsVisible() && !IsVisibleExoWindow(window)) {
       continue;
     }