Implement a ResourceThrottle for URL overriding in Chrome on Android.

chrome/browser/renderer_host/ignore_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/ignore_navigation_resource_throttle.h"
+
+#include "base/callback.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_view_host_delegate.h"
+#include "content/public/browser/resource_request_info.h"
+#include "content/public/browser/resource_throttle_controller.h"
+#include "content/public/common/referrer.h"
+#include "net/url_request/url_request.h"
+
+using content::BrowserThread;
+using content::Referrer;
+using content::RenderViewHost;
+using content::RenderViewHostDelegate;
+using content::ResourceRequestInfo;
+
+namespace {
+
+void CheckShouldIgnoreNavigationOnUiThread(

[darin (slow to review), 2012/05/23 18:18:29]

nit: UiThread -> UIThread

[mkosiba (inactive), 2012/05/28 16:06:52]

Done.

+    int render_process_id,
+    int render_view_id,
+    const GURL& url,
+    const Referrer& referrer,
+    bool is_content_initiated,
+    base::Callback<void(bool)> callback) {
+
+  RenderViewHost* render_view_host =
+      RenderViewHost::FromID(render_process_id, render_view_id);
+  RenderViewHostDelegate* render_view_host_delegate =
+      render_view_host ? render_view_host->GetDelegate() : NULL;
+  bool should_ignore_navigation = false;
+  if (render_view_host_delegate) {
+    should_ignore_navigation =
+        render_view_host_delegate->ShouldIgnoreNavigation(
+            render_view_host, url, referrer, is_content_initiated);
+  }
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(callback, should_ignore_navigation));
+}
+
+} // namespace
+
+IgnoreNavigationResourceThrottle::IgnoreNavigationResourceThrottle(
+    net::URLRequest* request)
+    : request_(request),
+      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+}
+
+IgnoreNavigationResourceThrottle::
+    ~IgnoreNavigationResourceThrottle() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+}
+
+void IgnoreNavigationResourceThrottle::WillStartRequest(bool* defer) {
+  *defer = ShouldDeferRequestForUrl(request_->url());

[darin (slow to review), 2012/05/23 18:18:29]

nit: ForUrl -> ForURL

[mkosiba (inactive), 2012/05/28 16:06:52]

Done.

+}
+
+void IgnoreNavigationResourceThrottle::WillRedirectRequest(
+    const GURL& new_url,
+    bool* defer) {
+  *defer = ShouldDeferRequestForUrl(new_url);
+}
+
+bool IgnoreNavigationResourceThrottle::ShouldDeferRequestForUrl(
+    const GURL& url) {
+  int render_process_id, render_view_id;
+  if (!ResourceRequestInfo::GetRenderViewForRequest(
+        request_,
+        &render_process_id,
+        &render_view_id)) {
+    return false;
+  }
+
+  const ResourceRequestInfo* info = ResourceRequestInfo::ForRequest(request_);

[darin (slow to review), 2012/05/23 18:18:29]

you should just call ResourceRequestInfo::GetAssociatedRenderView() here instead
of using GetRenderViewForRequest.

[mkosiba (inactive), 2012/05/28 16:06:52]

Done.

+  // The ShouldIngoreNavigationResourceThrottle should only be created for top

[darin (slow to review), 2012/05/23 18:18:29]

nit: what is a "ShouldIngoreNavigationResourceThrottle"?

[mkosiba (inactive), 2012/05/28 16:06:52]

Done.

+  // 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(&IgnoreNavigationResourceThrottle::OnResultObtained,
+                     weak_ptr_factory_.GetWeakPtr())));
+  return true;
+}
+
+void IgnoreNavigationResourceThrottle::OnResultObtained(
+    bool should_ignore_navigation) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  if (should_ignore_navigation) {
+    controller()->Cancel();

[darin (slow to review), 2012/05/23 18:18:29]

this may not be the ideal way to cancel the request in this case.  take a look
at how mailto: URLs get handled.  there we cancel the URLRequest so that its
status is URLRequestStatus::HANDLED_EXTERNALLY.  I think you are trying to
emulate that behavior, and so you need to make sure the URLRequest gets its
status set properly.  we may need to tweak the ResourceThrottleController
interface for this purpose.

[mkosiba (inactive), 2012/05/28 16:06:52]

Done.

+  } else {
+    controller()->Resume();
+  }
+}