feat(performspellcheck): queue spell check request asynchronously (#12112)

* feat(spellcheckrequest): implement spellcheckrequest

* feat(performspellcheck): queue spell check request asynchronously

atom/renderer/api/atom_api_spell_check_client.cc

@@ -9,6 +9,7 @@
 
 #include "atom/common/native_mate_converters/string16_converter.h"
 #include "base/logging.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "chrome/renderer/spellchecker/spellcheck_worditerator.h"
 #include "native_mate/converter.h"
 #include "native_mate/dictionary.h"
@@ -37,6 +38,27 @@ bool HasWordCharacters(const base::string16& text, int index) {
 
 }  // namespace
 
+class SpellCheckClient::SpellcheckRequest {
+ public:
+  SpellcheckRequest(const base::string16& text,
+                    blink::WebTextCheckingCompletion* completion)
+      : text_(text), completion_(completion) {
+    DCHECK(completion);
+  }
+  ~SpellcheckRequest() {}
+
+  base::string16 text() { return text_; }
+  blink::WebTextCheckingCompletion* completion() { return completion_; }
+
+ private:
+  base::string16 text_;  // Text to be checked in this task.
+
+  // The interface to send the misspelled ranges to WebKit.
+  blink::WebTextCheckingCompletion* completion_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpellcheckRequest);
+};
+
 SpellCheckClient::SpellCheckClient(const std::string& language,
                                    bool auto_spell_correct_turned_on,
                                    v8::Isolate* isolate,
@@ -74,14 +96,23 @@ void SpellCheckClient::RequestCheckingOfText(
     const blink::WebString& textToCheck,
     blink::WebTextCheckingCompletion* completionCallback) {
   base::string16 text(textToCheck.Utf16());
+  // Ignore invalid requests.
   if (text.empty() || !HasWordCharacters(text, 0)) {
     completionCallback->DidCancelCheckingText();
     return;
   }
 
-  std::vector<blink::WebTextCheckingResult> results;
-  SpellCheckText(text, false, &results);
-  completionCallback->DidFinishCheckingText(results);
+  // Clean up the previous request before starting a new request.
+  if (pending_request_param_.get()) {
+    pending_request_param_->completion()->DidCancelCheckingText();
+  }
+
+  pending_request_param_.reset(new SpellcheckRequest(text, completionCallback));
+
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE,
+      base::BindOnce(&SpellCheckClient::PerformSpellCheck, AsWeakPtr(),
+                     base::Owned(pending_request_param_.release())));
 }
 
 void SpellCheckClient::ShowSpellingUI(bool show) {}
@@ -190,6 +221,14 @@ bool SpellCheckClient::IsValidContraction(const SpellCheckScope& scope,
   return true;
 }
 
+void SpellCheckClient::PerformSpellCheck(SpellcheckRequest* param) {
+  DCHECK(param);
+
+  std::vector<blink::WebTextCheckingResult> results;
+  SpellCheckText(param->text(), false, &results);
+  param->completion()->DidFinishCheckingText(results);
+}
+
 SpellCheckClient::SpellCheckScope::SpellCheckScope(
     const SpellCheckClient& client)
     : handle_scope_(client.isolate_),

atom/renderer/api/atom_api_spell_check_client.h

@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "base/callback.h"
+#include "base/memory/weak_ptr.h"
 #include "chrome/renderer/spellchecker/spellcheck_worditerator.h"
 #include "native_mate/scoped_persistent.h"
 #include "third_party/WebKit/public/platform/WebSpellCheckPanelHostClient.h"
@@ -18,14 +19,15 @@
 namespace blink {
 struct WebTextCheckingResult;
 class WebTextCheckingCompletion;
-}
+}  // namespace blink
 
 namespace atom {
 
 namespace api {
 
 class SpellCheckClient : public blink::WebSpellCheckPanelHostClient,
-                         public blink::WebTextCheckClient {
+                         public blink::WebTextCheckClient,
+                         public base::SupportsWeakPtr<SpellCheckClient> {
  public:
   SpellCheckClient(const std::string& language,
                    bool auto_spell_correct_turned_on,
@@ -34,6 +36,7 @@ class SpellCheckClient : public blink::WebSpellCheckPanelHostClient,
   virtual ~SpellCheckClient();
 
  private:
+  class SpellcheckRequest;
   // blink::WebTextCheckClient:
   void CheckSpelling(
       const blink::WebString& text,
@@ -73,6 +76,9 @@ class SpellCheckClient : public blink::WebSpellCheckPanelHostClient,
   bool IsValidContraction(const SpellCheckScope& scope,
                           const base::string16& word);
 
+  // Performs spell checking from the request queue.
+  void PerformSpellCheck(SpellcheckRequest* param);
+
   // Represents character attributes used for filtering out characters which
   // are not supported by this SpellCheck object.
   SpellcheckCharAttribute character_attributes_;
@@ -85,6 +91,11 @@ class SpellCheckClient : public blink::WebSpellCheckPanelHostClient,
   SpellcheckWordIterator text_iterator_;
   SpellcheckWordIterator contraction_iterator_;
 
+  // The parameters of a pending background-spellchecking request.
+  // (When WebKit sends two or more requests, we cancel the previous
+  // requests so we do not have to use vectors.)
+  std::unique_ptr<SpellcheckRequest> pending_request_param_;
+
   v8::Isolate* isolate_;
   v8::Persistent<v8::Context> context_;
   mate::ScopedPersistent<v8::Object> provider_;