Ensure simulated events are only passed on tab/shift-tab

Currently simulated tab events are sent to PDF plugin whenever PDF
plugin is focused. Ensure that simulated tab events are only passed in
case of focus received from tab/shift-tab.

Bug: 989046
Change-Id: I994d401f6896bc7dcb6f41669c38757b52413873
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2224881Reviewed-by: Kevin Babbitt <kbabbitt@microsoft.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Ankit Kumar 🌪️ <ankk@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#774976}

chrome/browser/pdf/pdf_extension_test.cc

@@ -2643,21 +2643,28 @@ IN_PROC_BROWSER_TEST_F(PDFExtensionTest, TabInAndOutOfPDFPlugin) {
   content::WebContents* guest_contents = LoadPdfGetGuestContents(test_pdf_url);
   ASSERT_TRUE(guest_contents);
 
-  // Set focus on PDF document.
-  ASSERT_TRUE(content::ExecuteScript(
-      guest_contents, "document.getElementById('plugin').focus();"));
-
-  // The script will ensure we return the id of the focused element on focus.
-  std::string script =
-      "function onFocus(e) {"
-      "  domAutomationController.send(e.target.id);"
-      "}"
-      "const plugin = document.getElementById('plugin');"
-      "const button = "
-      "document.getElementById('zoom-toolbar').$['zoom-out-button'];"
-      "plugin.addEventListener('focus', onFocus);"
-      "button.addEventListener('focus', onFocus);";
-  ASSERT_TRUE(content::ExecuteScript(guest_contents, script));
+  // Set focus on last toolbar element (zoom-out-button).
+  ASSERT_TRUE(content::ExecuteScript(guest_contents,
+                                     R"(document.getElementById('zoom-toolbar')
+                                            .$['zoom-out-button']
+                                            .$$('cr-icon-button')
+                                            .focus();)"));
+
+  // The script will ensure we return the the focused element on focus.
+  const char kScript[] = R"(
+    const plugin = document.getElementById('plugin');
+    plugin.addEventListener('focus', () => {
+      window.domAutomationController.send('plugin');
+    });
+
+    const button = document.getElementById('zoom-toolbar')
+                   .$['zoom-out-button']
+                   .$$('cr-icon-button');
+    button.addEventListener('focus', () => {
+      window.domAutomationController.send('zoom-out-button');
+    });
+  )";
+  ASSERT_TRUE(content::ExecuteScript(guest_contents, kScript));
 
   // Helper to simulate a tab press and wait for a focus message.
   auto press_tab_and_wait_for_message = [guest_contents](bool reverse) {
@@ -2669,11 +2676,11 @@ IN_PROC_BROWSER_TEST_F(PDFExtensionTest, TabInAndOutOfPDFPlugin) {
     return reply;
   };
 
+  // Press <tab> and ensure that PDF document receives focus.
+  EXPECT_EQ("\"plugin\"", press_tab_and_wait_for_message(false));
   // Press <shift-tab> and ensure that last toolbar element (zoom-out-button)
   // receives focus.
   EXPECT_EQ("\"zoom-out-button\"", press_tab_and_wait_for_message(true));
-  // Press <tab> and ensure that PDF document receives focus.
-  EXPECT_EQ("\"plugin\"", press_tab_and_wait_for_message(false));
 }
 
 // This test suite does a simple text-extraction based on the accessibility

content/renderer/pepper/pepper_webplugin_impl.cc

@@ -221,17 +221,27 @@ void PepperWebPluginImpl::UpdateFocus(bool focused,
     instance_->SetWebKitFocus(focused);
 
     if (focused && instance_->SupportsKeyboardFocus()) {
-      int modifiers = blink::WebInputEvent::kNoModifiers;
-      if (focus_type == blink::mojom::FocusType::kBackward)
-        modifiers |= blink::WebInputEvent::kShiftKey;
-      // As part of focus management for plugin, blink brings plugin to focus
-      // but does not forward the tab event to plugin. Hence simulating tab
-      // event here to enable seamless tabbing across UI & plugin.
-      blink::WebKeyboardEvent simulated_event(
-          blink::WebInputEvent::Type::kKeyDown, modifiers, base::TimeTicks());
-      simulated_event.windows_key_code = ui::KeyboardCode::VKEY_TAB;
-      ui::Cursor cursor;
-      instance_->HandleInputEvent(simulated_event, &cursor);
+      switch (focus_type) {
+        case blink::mojom::FocusType::kForward:
+        case blink::mojom::FocusType::kBackward: {
+          int modifiers = blink::WebInputEvent::kNoModifiers;
+          if (focus_type == blink::mojom::FocusType::kBackward)
+            modifiers |= blink::WebInputEvent::kShiftKey;
+          // As part of focus management for plugin, blink brings plugin to
+          // focus but does not forward the tab event to plugin. Hence
+          // simulating tab event here to enable seamless tabbing across UI &
+          // plugin.
+          blink::WebKeyboardEvent simulated_event(
+              blink::WebInputEvent::Type::kKeyDown, modifiers,
+              base::TimeTicks());
+          simulated_event.windows_key_code = ui::KeyboardCode::VKEY_TAB;
+          ui::Cursor cursor;
+          instance_->HandleInputEvent(simulated_event, &cursor);
+          break;
+        }
+        default:
+          break;
+      }
     }
   }
 }