Make autotestPrivate.setClipboardTextData synchronous

The ChromeOS clipboard used to be synchronously written within
the browser process, but now it is asynchronously updated
(see ui/base/clipboard/clipboard_ozone.cc for the details).

Because of that, autotestPrivate.setClipboardTextData may return
earlier than the clipboard data is actually set occasionally.
To deal with such case, this CL introduces a clipboard observer
to ensure that the clipboard is written.

Bug: 1167256
Test: the new test cases
Change-Id: I167be3aee090465e30951fbb7a9db688429059c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2634121
Commit-Queue: Jun Mukai <mukai@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845060}

chrome/browser/chromeos/extensions/autotest_private/autotest_private_api.cc

@@ -1958,11 +1958,15 @@ AutotestPrivateGetClipboardTextDataFunction::Run() {
 // AutotestPrivateSetClipboardTextDataFunction
 ///////////////////////////////////////////////////////////////////////////////
 
+AutotestPrivateSetClipboardTextDataFunction::
+    AutotestPrivateSetClipboardTextDataFunction() = default;
+
 AutotestPrivateSetClipboardTextDataFunction::
     ~AutotestPrivateSetClipboardTextDataFunction() = default;
 
 ExtensionFunction::ResponseAction
 AutotestPrivateSetClipboardTextDataFunction::Run() {
+  observation_.Observe(ui::ClipboardMonitor::GetInstance());
   std::unique_ptr<api::autotest_private::SetClipboardTextData::Params> params(
       api::autotest_private::SetClipboardTextData::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params);
@@ -1971,7 +1975,12 @@ AutotestPrivateSetClipboardTextDataFunction::Run() {
   ui::ScopedClipboardWriter clipboard_writer(ui::ClipboardBuffer::kCopyPaste);
   clipboard_writer.WriteText(data);
 
-  return RespondNow(NoArguments());
+  return did_respond() ? AlreadyResponded() : RespondLater();
+}
+
+void AutotestPrivateSetClipboardTextDataFunction::OnClipboardDataChanged() {
+  observation_.Reset();
+  Respond(NoArguments());
 }
 
 ///////////////////////////////////////////////////////////////////////////////

chrome/browser/chromeos/extensions/autotest_private/autotest_private_api.h

@@ -14,6 +14,7 @@
 #include "ash/rotator/screen_rotation_animator_observer.h"
 #include "base/compiler_specific.h"
 #include "base/optional.h"
+#include "base/scoped_observation.h"
 #include "base/scoped_observer.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/chromeos/printing/cups_printers_manager.h"
@@ -378,14 +379,24 @@ class AutotestPrivateGetClipboardTextDataFunction : public ExtensionFunction {
   ResponseAction Run() override;
 };
 
-class AutotestPrivateSetClipboardTextDataFunction : public ExtensionFunction {
+class AutotestPrivateSetClipboardTextDataFunction
+    : public ExtensionFunction,
+      public ui::ClipboardObserver {
  public:
+  AutotestPrivateSetClipboardTextDataFunction();
+
   DECLARE_EXTENSION_FUNCTION("autotestPrivate.setClipboardTextData",
                              AUTOTESTPRIVATE_SETCLIPBOARDTEXTDATA)
 
  private:
   ~AutotestPrivateSetClipboardTextDataFunction() override;
   ResponseAction Run() override;
+
+  // ui::ClipboardObserver:
+  void OnClipboardDataChanged() override;
+
+  base::ScopedObservation<ui::ClipboardMonitor, ui::ClipboardObserver>
+      observation_{this};
 };
 
 class AutotestPrivateSetCrostiniEnabledFunction : public ExtensionFunction {

chrome/test/data/extensions/api_test/autotest_private/test.js

@@ -993,6 +993,31 @@ var defaultTests = [
     });
   },
 
+  function setAndGetClipboardTextData() {
+    const textData = 'foo bar';
+    chrome.autotestPrivate.getClipboardTextData(function(beforeData) {
+      chrome.test.assertTrue(textData != beforeData);
+      chrome.autotestPrivate.setClipboardTextData(textData, function() {
+        chrome.autotestPrivate.getClipboardTextData(function(afterData) {
+          chrome.test.assertEq(afterData, textData);
+          chrome.test.succeed();
+        });
+      });
+    });
+  },
+
+  function setClipboardTextDataTwice() {
+    const textData = 'twice clipboard data';
+    chrome.autotestPrivate.setClipboardTextData(textData, function() {
+      chrome.autotestPrivate.setClipboardTextData(textData, function() {
+        chrome.autotestPrivate.getClipboardTextData(function(data) {
+          chrome.test.assertEq(data, textData);
+          chrome.test.succeed();
+        });
+      });
+    });
+  },
+
   // KEEP |lockScreen()| TESTS AT THE BOTTOM OF THE defaultTests AS IT WILL
   // CHANGE THE SESSION STATE TO LOCKED STATE.
   function lockScreen() {