inputs: Add lacros browser test for sending backspace keys.

Bug: b/264825502
Change-Id: I29df0f632aa48176955ff85c35d31699f7153498
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4199115
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1098411}

chrome/browser/lacros/input_method_lacros_browsertest.cc

@@ -410,6 +410,45 @@ IN_PROC_BROWSER_TEST_F(InputMethodLacrosBrowserTest,
                                          "abc", gfx::Range(3)));
 }
 
+IN_PROC_BROWSER_TEST_F(InputMethodLacrosBrowserTest,
+                       SendBackspaceDeletesNonEmptyTextField) {
+  mojo::Remote<InputMethodTestInterface> input_method =
+      BindInputMethodTestInterface(
+          {InputMethodTestInterface::MethodMinVersions::kWaitForFocusMinVersion,
+           InputMethodTestInterface::MethodMinVersions::
+               kKeyEventHandledMinVersion});
+  if (!input_method.is_bound()) {
+    GTEST_SKIP() << "Unsupported ash version";
+  }
+  const std::string id = RenderAutofocusedInputFieldInLacros(browser());
+  ASSERT_TRUE(SetInputFieldText(GetActiveWebContents(browser()), id, "hello",
+                                gfx::Range(3)));
+  InputMethodTestInterfaceAsyncWaiter input_method_async_waiter(
+      input_method.get());
+  input_method_async_waiter.WaitForFocus();
+
+  SendKeyEventSync(input_method_async_waiter,
+                   CreateKeyPressEvent('\b', ui::DomCode::BACKSPACE));
+  SendKeyEventSync(input_method_async_waiter,
+                   CreateKeyReleaseEvent('\b', ui::DomCode::BACKSPACE));
+  EXPECT_TRUE(WaitUntilInputFieldHasText(GetActiveWebContents(browser()), id,
+                                         "helo", gfx::Range(2)));
+
+  SendKeyEventSync(input_method_async_waiter,
+                   CreateKeyPressEvent('\b', ui::DomCode::BACKSPACE));
+  SendKeyEventSync(input_method_async_waiter,
+                   CreateKeyReleaseEvent('\b', ui::DomCode::BACKSPACE));
+  EXPECT_TRUE(WaitUntilInputFieldHasText(GetActiveWebContents(browser()), id,
+                                         "hlo", gfx::Range(1)));
+
+  SendKeyEventSync(input_method_async_waiter,
+                   CreateKeyPressEvent('\b', ui::DomCode::BACKSPACE));
+  SendKeyEventSync(input_method_async_waiter,
+                   CreateKeyReleaseEvent('\b', ui::DomCode::BACKSPACE));
+  EXPECT_TRUE(WaitUntilInputFieldHasText(GetActiveWebContents(browser()), id,
+                                         "lo", gfx::Range(0)));
+}
+
 IN_PROC_BROWSER_TEST_F(InputMethodLacrosBrowserTest,
                        SetCompositionWhileHandlingKeyEvent) {
   mojo::Remote<InputMethodTestInterface> input_method =