[page_load_metrics] Add a NavigationThrottle for richer abort metrics

content/public/test/browser_test_utils.cc

Index: content/public/test/browser_test_utils.cc
diff --git a/content/public/test/browser_test_utils.cc b/content/public/test/browser_test_utils.cc
index ca51b0575028171c30990b686532a6c518739d2a..b155835ff7c32fabb7c864375e4f3accbfe42fe8 100644
--- a/content/public/test/browser_test_utils.cc
+++ b/content/public/test/browser_test_utils.cc
@@ -43,6 +43,8 @@
 #include "content/public/browser/browser_plugin_guest_manager.h"
 #include "content/public/browser/histogram_fetcher.h"
 #include "content/public/browser/navigation_entry.h"
+#include "content/public/browser/navigation_handle.h"
+#include "content/public/browser/navigation_throttle.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_frame_host.h"
@@ -346,6 +348,40 @@ CrossSiteRedirectResponseHandler(const GURL& server_base_url,
   return std::move(http_response);
 }
 
+// Helper class used by the TestNavigationManager to pause navigations.
+// Note: the throttle should be added to the *end* of the list of throttles,
+// so all NavigationThrottles that should be attached observe the
+// WillStartRequest callback. This throttle is added, and will re-add itself
+// to the end of the list on WillStartRequest.
+class TestNavigationManagerThrottle : public NavigationThrottle {
+ public:
+  TestNavigationManagerThrottle(NavigationHandle* handle,
+                                base::Closure on_will_start_request_closure,
+                                bool attached_in_did_start)
+      : NavigationThrottle(handle),
+        on_will_start_request_closure_(on_will_start_request_closure),
+        attached_in_did_start_(attached_in_did_start) {}
+  ~TestNavigationManagerThrottle() override {}
+
+ private:
+  // NavigationThrottle implementation.
+  NavigationThrottle::ThrottleCheckResult WillStartRequest() override {

[clamy, 2016/07/26 17:09:22]

I'm not terribly fond of this. Attaching a throttle twice is really hard to
understand, and may break easily if we want to add the functionality of waiting
for redirects/ready to commit to the testNavigationManger (which we may want to
do in the future).

Instead, I would suggest adding a method to NavigationHandleImpl to attach the
throttle to the end.

[Charlie Harrison, 2016/07/26 19:56:06]

Hm okay. I've modified NavigationHandleImpl::RegisterNavigationThrottles so that
the normal throttles are added to the beginning. Does that seem ok to you?

+    if (attached_in_did_start_) {
+      navigation_handle()->RegisterThrottleForTesting(
+          base::WrapUnique(new TestNavigationManagerThrottle(
+              navigation_handle(), on_will_start_request_closure_, false)));
+      return NavigationThrottle::PROCEED;
+    } else {
+      BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                              on_will_start_request_closure_);
+      return NavigationThrottle::DEFER;
+    }
+  }
+
+  base::Closure on_will_start_request_closure_;
+  bool attached_in_did_start_;
+};
+
 }  // namespace
 
 bool NavigateIframeToURL(WebContents* web_contents,
@@ -1431,4 +1467,94 @@ uint32_t InputMsgWatcher::WaitForAck() {
   return ack_result_;
 }
 
+TestNavigationManager::TestNavigationManager(int filtering_frame_tree_node_id,
+                                             WebContents* web_contents,
+                                             const GURL& url)
+    : WebContentsObserver(web_contents),
+      filtering_frame_tree_node_id_(filtering_frame_tree_node_id),
+      url_(url),
+      navigation_paused_(false),
+      handle_(nullptr),
+      handled_navigation_(false),
+      weak_factory_(this) {}
+
+TestNavigationManager::TestNavigationManager(WebContents* web_contents,
+                                             const GURL& url)
+    : TestNavigationManager(FrameTreeNode::kFrameTreeNodeInvalidId,
+                            web_contents,
+                            url) {}
+
+TestNavigationManager::~TestNavigationManager() {
+  ResumeNavigation();
+}
+
+void TestNavigationManager::WaitForWillStartRequest() {
+  DCHECK(!did_finish_loop_runner_);
+  if (!handle_ && handled_navigation_)
+    return;
+  if (navigation_paused_)
+    return;
+  will_start_loop_runner_ = new MessageLoopRunner();
+  will_start_loop_runner_->Run();
+  will_start_loop_runner_ = nullptr;
+}
+
+void TestNavigationManager::WaitForNavigationFinished() {
+  DCHECK(!will_start_loop_runner_);
+  if (!handle_ && handled_navigation_)
+    return;
+  // Ensure the navigation is resumed if the manager paused it previously.
+  if (navigation_paused_)
+    ResumeNavigation();
+  did_finish_loop_runner_ = new MessageLoopRunner();
+  did_finish_loop_runner_->Run();
+  did_finish_loop_runner_ = nullptr;
+}
+
+void TestNavigationManager::DidStartNavigation(NavigationHandle* handle) {
+  if (handle_ || handle->GetURL() != url_)
+    return;
+  if (handled_navigation_)
+    return;
+
+  if (filtering_frame_tree_node_id_ != FrameTreeNode::kFrameTreeNodeInvalidId &&
+      handle->GetFrameTreeNodeId() != filtering_frame_tree_node_id_) {
+    return;
+  }
+
+  handle_ = handle;
+  std::unique_ptr<NavigationThrottle> throttle(
+      new TestNavigationManagerThrottle(
+          handle_, base::Bind(&TestNavigationManager::OnWillStartRequest,
+                              weak_factory_.GetWeakPtr()), true));
+  handle_->RegisterThrottleForTesting(std::move(throttle));
+}
+
+void TestNavigationManager::DidFinishNavigation(NavigationHandle* handle) {
+  if (handle != handle_)
+    return;
+  handle_ = nullptr;
+  handled_navigation_ = true;
+  navigation_paused_ = false;
+  if (did_finish_loop_runner_)

[clamy, 2016/07/26 17:09:22]

We may want to also quit the will_start_loop_runner_ here, and have
TestNavigationManager::WaitForWillStartRequest return a boolean. With the
throttle being in last position, people may want to wait for the start of the
request that is cancelled by another throttle (and ensure it doesn't start).

[Charlie Harrison, 2016/07/26 19:56:07]

Done.

+    did_finish_loop_runner_->Quit();
+}
+
+void TestNavigationManager::OnWillStartRequest() {
+  navigation_paused_ = true;
+  if (will_start_loop_runner_)
+    will_start_loop_runner_->Quit();
+
+  // If waiting for the navigation to finish, resume the navigation.
+  if (did_finish_loop_runner_)
+    ResumeNavigation();
+}
+
+void TestNavigationManager::ResumeNavigation() {
+  if (!navigation_paused_ || !handle_)
+    return;
+  navigation_paused_ = false;
+  handle_->Resume();
+}
+
 }  // namespace content