[Android] Java Bridge: handle requests from Java Script on the background thread

content/browser/android/java/gin_java_method_invocation_helper.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_ANDROID_JAVA_GIN_JAVA_METHOD_INVOCATION_HELPER_H_
 #define CONTENT_BROWSER_ANDROID_JAVA_GIN_JAVA_METHOD_INVOCATION_HELPER_H_
 
 #include <map>
 
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/memory/ref_counted.h"
 #include "base/values.h"
 #include "content/browser/android/java/gin_java_bound_object.h"
 #include "content/browser/android/java/java_type.h"
 #include "content/common/android/gin_java_bridge_errors.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 class JavaMethod;
 
-// Instances of this class are created and initialized on the UI thread, do

[benm (inactive), 2014/12/05 17:09:33]

Can we keep a comment here about the threading please (fixed up as needed of
course :-))

[mnaganov (inactive), 2014/12/05 18:07:40]

Done.

-// their work on the background thread, and then again examined on the UI
-// thread. They don't work on both threads simultaneously, though.
 class CONTENT_EXPORT GinJavaMethodInvocationHelper
     : public base::RefCountedThreadSafe<GinJavaMethodInvocationHelper> {
  public:
-  // DispatcherDelegate is used on the UI thread
   class DispatcherDelegate {
    public:
     DispatcherDelegate() {}
     virtual ~DispatcherDelegate() {}
     virtual JavaObjectWeakGlobalRef GetObjectWeakRef(
         GinJavaBoundObject::ObjectID object_id) = 0;
 
    private:
     DISALLOW_COPY_AND_ASSIGN(DispatcherDelegate);
   };
 
-  // ObjectDelegate is used in the background thread
   class ObjectDelegate {
    public:
     ObjectDelegate() {}
     virtual ~ObjectDelegate() {}
     virtual base::android::ScopedJavaLocalRef<jobject> GetLocalRef(
         JNIEnv* env) = 0;
     virtual base::android::ScopedJavaLocalRef<jclass> GetLocalClassRef(
         JNIEnv* env) = 0;
     virtual const JavaMethod* FindMethod(const std::string& method_name,
                                          size_t num_parameters) = 0;
@@ skipping 56 matching lines @@
   GinJavaBridgeError invocation_error_;
   base::android::ScopedJavaGlobalRef<jobject> object_result_;
   base::android::ScopedJavaGlobalRef<jclass> safe_annotation_clazz_;
 
   DISALLOW_COPY_AND_ASSIGN(GinJavaMethodInvocationHelper);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_JAVA_GIN_JAVA_METHOD_INVOCATION_HELPER_H_