Implement a ResourceThrottle for URL overriding in Chrome on Android.

chrome/browser/renderer_host/intercept_navigation_resource_throttle.cc

+// 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.
+
+#include "chrome/browser/renderer_host/intercept_navigation_resource_throttle.h"
+
+#include "base/callback.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/child_process_security_policy.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/resource_request_info.h"
+#include "content/public/browser/resource_throttle_controller.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/browser/web_contents_delegate.h"
+#include "content/public/common/referrer.h"
+#include "net/url_request/url_request.h"
+
+using content::BrowserThread;
+using content::ChildProcessSecurityPolicy;
+using content::Referrer;
+using content::RenderViewHost;
+using content::ResourceRequestInfo;
+using content::WebContents;
+using content::WebContentsDelegate;
+
+namespace {
+
+void CheckShouldIgnoreNavigationOnUIThread(
+    int render_process_id,
+    int render_view_id,
+    const GURL& url,
+    const Referrer& referrer,
+    bool is_content_initiated,
+    base::Callback<void(bool)> callback) {
+
+  RenderViewHost* rvh =
+      RenderViewHost::FromID(render_process_id, render_view_id);
+  WebContents* web_contents =
+      rvh ? WebContents::FromRenderViewHost(rvh) : NULL;
+  WebContentsDelegate* web_contents_delegate =
+      web_contents ? web_contents->GetDelegate() : NULL;
+
+  GURL validated_url(url);
+  RenderViewHost::FilterURL(
+      ChildProcessSecurityPolicy::GetInstance(),
+      rvh->GetProcess()->GetID(),
+      false,
+      &validated_url);
+
+  bool should_ignore_navigation = false;
+  if (web_contents_delegate) {
+    should_ignore_navigation = web_contents_delegate->ShouldIgnoreNavigation(
+            web_contents, validated_url, referrer, is_content_initiated);
+  }
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(callback, should_ignore_navigation));
+}
+
+} // namespace
+
+InterceptNavigationResourceThrottle::InterceptNavigationResourceThrottle(
+    net::URLRequest* request)
+    : request_(request),
+      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+}
+
+InterceptNavigationResourceThrottle::
+    ~InterceptNavigationResourceThrottle() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+}
+
+void InterceptNavigationResourceThrottle::WillStartRequest(bool* defer) {
+  *defer = ShouldDeferRequestForURL(request_->url());
+}
+
+void InterceptNavigationResourceThrottle::WillRedirectRequest(
+    const GURL& new_url,
+    bool* defer) {
+  *defer = ShouldDeferRequestForURL(new_url);
+}
+
+bool InterceptNavigationResourceThrottle::ShouldDeferRequestForURL(
+    const GURL& url) {
+  const ResourceRequestInfo* info = ResourceRequestInfo::ForRequest(request_);
+  if (!info)
+    return false;
+
+  int render_process_id, render_view_id;
+  if (!info->GetAssociatedRenderView(&render_process_id, &render_view_id)) {
+    return false;
+  }
+
+  // This class should only be instantiated for top level frame requests.
+  DCHECK(info->IsMainFrame());
+
+  BrowserThread::PostTask(
+      BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(
+          &CheckShouldIgnoreNavigationOnUIThread,
+          render_process_id,
+          render_view_id,
+          url,
+          Referrer(GURL(request_->referrer()), info->GetReferrerPolicy()),
+          info->HasUserGesture(),
+          base::Bind(&InterceptNavigationResourceThrottle::OnResultObtained,
+                     weak_ptr_factory_.GetWeakPtr())));
+  return true;
+}
+
+void InterceptNavigationResourceThrottle::OnResultObtained(
+    bool should_ignore_navigation) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  if (should_ignore_navigation) {
+    // TODO: Cancel() results in a CANCELLED status but what we really want is
+    // a HANDLED_EXTERNALLY status.
+    controller()->Cancel();
+  } else {
+    controller()->Resume();
+  }
+}