[android_webview] Don't block the IO thread when reading from an InputStream.

android_webview/native/android_stream_reader_url_request_job.h

-// Copyright (c) 2012 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 ANDROID_WEBVIEW_NATIVE_ANDROID_STREAM_READER_URL_REQUEST_JOB_H_
-#define ANDROID_WEBVIEW_NATIVE_ANDROID_STREAM_READER_URL_REQUEST_JOB_H_
-
-#include "base/android/scoped_java_ref.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "base/threading/non_thread_safe.h"
-#include "net/http/http_byte_range.h"
-#include "net/url_request/url_request_job.h"
-
-namespace net {
-class URLRequest;
-}
-
-// A request job that reads data from a Java InputStream.
-class AndroidStreamReaderURLRequestJob : public net::URLRequestJob {
- public:
-  /*
-   * We use a delegate so that we can share code for this job in slightly
-   * different contexts.
-   */
-  class Delegate {
-   public:
-    virtual base::android::ScopedJavaLocalRef<jobject> OpenInputStream(
-        JNIEnv* env,
-        net::URLRequest* request) = 0;
-
-    virtual bool GetMimeType(
-        JNIEnv* env,
-        net::URLRequest* request,
-        jobject stream,
-        std::string* mime_type) = 0;
-
-    virtual bool GetCharset(
-        JNIEnv* env,
-        net::URLRequest* request,
-        jobject stream,
-        std::string* charset) = 0;
-
-    virtual ~Delegate() {}
-  };
-
-  AndroidStreamReaderURLRequestJob(
-      net::URLRequest* request,
-      net::NetworkDelegate* network_delegate,
-      scoped_ptr<Delegate> delegate);
-
-  // URLRequestJob:
-  virtual void Start() OVERRIDE;
-  virtual bool ReadRawData(net::IOBuffer* buf,
-                           int buf_size,
-                           int* bytes_read) OVERRIDE;
-  virtual void SetExtraRequestHeaders(
-      const net::HttpRequestHeaders& headers) OVERRIDE;
-  virtual bool GetMimeType(std::string* mime_type) const OVERRIDE;
-  virtual bool GetCharset(std::string* charset) OVERRIDE;
-
- protected:
-  virtual ~AndroidStreamReaderURLRequestJob();
-
- private:
-  // Verify the requested range against the stream size.
-  bool VerifyRequestedRange(JNIEnv* env);
-
-  // Skip to the first byte of the requested read range.
-  bool SkipToRequestedRange(JNIEnv* env);
-
-  void StartAsync();
-
-  net::HttpByteRange byte_range_;
-  scoped_ptr<Delegate> delegate_;
-  base::android::ScopedJavaGlobalRef<jobject> stream_;
-  base::android::ScopedJavaGlobalRef<jbyteArray> buffer_;
-  base::WeakPtrFactory<AndroidStreamReaderURLRequestJob> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(AndroidStreamReaderURLRequestJob);
-};
-
-bool RegisterAndroidStreamReaderUrlRequestJob(JNIEnv* env);
-
-#endif  // ANDROID_WEBVIEW_NATIVE_ANDROID_STREAM_READER_URL_REQUEST_JOB_H_