Android: Use a ResourceThrottle to intercept GET downloads.

chrome/browser/android/intercept_download_resource_throttle.h

Index: chrome/browser/android/intercept_download_resource_throttle.h
diff --git a/chrome/browser/android/intercept_download_resource_throttle.h b/chrome/browser/android/intercept_download_resource_throttle.h
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+++ b/chrome/browser/android/intercept_download_resource_throttle.h
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+// Copyright 2013 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 CHROME_BROWSER_ANDROID_INTERCEPT_DOWNLOAD_RESOURCE_THROTTLE_H_
+#define CHROME_BROWSER_ANDROID_INTERCEPT_DOWNLOAD_RESOURCE_THROTTLE_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "content/public/browser/resource_throttle.h"
+
+namespace net {
+class URLRequest;
+}
+
+namespace chrome {
+
+// InterceptDownloadResourceThrottle checks if a download request should be
+// handled by Chrome or passsed to the Android Download Manager.
+class InterceptDownloadResourceThrottle : public content::ResourceThrottle {
+ public:
+  InterceptDownloadResourceThrottle(net::URLRequest* request,
+                                    int render_process_id,
+                                    int render_view_id,
+                                    int request_id);
+
+  // content::ResourceThrottle implementation:
+  virtual void WillStartRequest(bool* defer) OVERRIDE;
+  virtual void WillProcessResponse(bool* defer) OVERRIDE;
+
+ private:
+  virtual ~InterceptDownloadResourceThrottle();
+
+  void ProcessDownloadRequest();
+  // Set to true when if we want chrome to handle the download.
+  const net::URLRequest* request_;
+  int render_process_id_;
+  int render_view_id_;
+  int request_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(InterceptDownloadResourceThrottle);
+};
+
+}  // namespace
+
+#endif  // CHROME_BROWSER_ANDROID_INTERCEPT_DOWNLOAD_RESOURCE_THROTTLE_H_