Adding Navigation Throttles to DevTools

content/browser/devtools/render_frame_devtools_agent_host.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 "content/browser/devtools/render_frame_devtools_agent_host.h"
 
 #include <tuple>
 #include <utility>
 
 #include "base/lazy_instance.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/devtools/devtools_frame_trace_recorder.h"
 #include "content/browser/devtools/devtools_protocol_handler.h"
+#include "content/browser/devtools/page_navigation_throttle.h"
 #include "content/browser/devtools/protocol/browser_handler.h"
 #include "content/browser/devtools/protocol/dom_handler.h"
 #include "content/browser/devtools/protocol/emulation_handler.h"
 #include "content/browser/devtools/protocol/input_handler.h"
 #include "content/browser/devtools/protocol/inspector_handler.h"
 #include "content/browser/devtools/protocol/io_handler.h"
 #include "content/browser/devtools/protocol/network_handler.h"
 #include "content/browser/devtools/protocol/page_handler.h"
 #include "content/browser/devtools/protocol/security_handler.h"
 #include "content/browser/devtools/protocol/service_worker_handler.h"
@@ skipping 312 matching lines @@
 // static
 void RenderFrameDevToolsAgentHost::OnBeforeNavigation(
     NavigationHandle* navigation_handle) {
   FrameTreeNode* frame_tree_node =
       static_cast<NavigationHandleImpl*>(navigation_handle)->frame_tree_node();
   RenderFrameDevToolsAgentHost* agent_host = FindAgentHost(frame_tree_node);
   if (agent_host)
     agent_host->AboutToNavigate(navigation_handle);
 }
 
+// static
+std::unique_ptr<NavigationThrottle>
+RenderFrameDevToolsAgentHost::GetThrottleForNavigation(
+    NavigationHandle* navigation_handle) {
+  // NOTE a single throttle registered by Page.setControlNavigations is intended

[nasko, 2016/07/13 22:37:34]

This comment is not entirely correct. Each navigation is 1:1 with
NavigationHandle and in turn NavigationHandle is associated with a
NavigationThrottle. One throttle cannot handle multiple navigations. 

[alex clarke (OOO till 29th), 2016/07/14 16:06:05]

Acknowledged.

+  // to control navigations in the main frame and all child frames.
+  FrameTreeNode* frame_tree_node =
+      static_cast<NavigationHandleImpl*>(navigation_handle)->frame_tree_node();
+  while (frame_tree_node && frame_tree_node->parent()) {
+    frame_tree_node = frame_tree_node->parent();
+  }
+  RenderFrameDevToolsAgentHost* agent_host = FindAgentHost(frame_tree_node);
+  if (agent_host && agent_host->page_handler_) {

[nasko, 2016/07/13 22:37:34]

After offline chat with dgozman@, it became more clear to me that page_handler_
only exists for the main frame. This is definitely something that wasn't obvious
to me, so let's make sure we put a comment on this method.
Also, it makes the above comment obsolete and what is one thing that is common
across all navigations is the PageHadnler object.

[alex clarke (OOO till 29th), 2016/07/14 16:06:05]

Done.

+    return agent_host->page_handler_->GetThrottleForNavigation(
+        navigation_handle);
+  }
+  return nullptr;
+}
+
 RenderFrameDevToolsAgentHost::RenderFrameDevToolsAgentHost(
     RenderFrameHostImpl* host)
     : browser_handler_(new devtools::browser::BrowserHandler()),
       dom_handler_(new devtools::dom::DOMHandler()),
       input_handler_(new devtools::input::InputHandler()),
       inspector_handler_(new devtools::inspector::InspectorHandler()),
       io_handler_(new devtools::io::IOHandler(GetIOContext())),
       network_handler_(new devtools::network::NetworkHandler()),
       page_handler_(nullptr),
       security_handler_(nullptr),
@@ skipping 564 matching lines @@
     RenderFrameHost* host) {
   return (current_ && current_->host() == host) ||
       (pending_ && pending_->host() == host);
 }
 
 bool RenderFrameDevToolsAgentHost::IsChildFrame() {
   return current_ && current_->host()->GetParent();
 }
 
 }  // namespace content