Make resource throttles and AsyncResourceHandler add events to NetLog

when they block a request.  This is aimed at making issues easier to
debug when a delegate defers an request for significant periods of time.

Also display that information in about:net-internals when a request is
already active and blocked on a delegate.

BUG=94920

Review URL: https://codereview.chromium.org/25108004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238746 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 31 insertions, 14 deletions

diff --git a/content/browser/loader/throttling_resource_handler.cc b/content/browser/loader/throttling_resource_handler.cc
index 23f77da..36c595f 100644
--- a/content/browser/loader/throttling_resource_handler.cc
+++ b/content/browser/loader/throttling_resource_handler.cc
@@ -7,6 +7,7 @@
 #include "content/browser/loader/resource_request_info_impl.h"
 #include "content/public/browser/resource_throttle.h"
 #include "content/public/common/resource_response.h"
+#include "net/url_request/url_request.h"
 
 namespace content {
 
@@ -17,10 +18,14 @@ ThrottlingResourceHandler::ThrottlingResourceHandler(
     : LayeredResourceHandler(request, next_handler.Pass()),
       deferred_stage_(DEFERRED_NONE),
       throttles_(throttles.Pass()),
-      index_(0),
+      next_index_(0),
       cancelled_by_resource_throttle_(false) {
-  for (size_t i = 0; i < throttles_.size(); ++i)
+  for (size_t i = 0; i < throttles_.size(); ++i) {
     throttles_[i]->set_controller(this);
+    // Throttles must have a name, as otherwise, bugs where a throttle fails
+    // to resume a request can be very difficult to debug.
+    DCHECK(throttles_[i]->GetNameForLogging());
+  }
 }
 
 ThrottlingResourceHandler::~ThrottlingResourceHandler() {
@@ -33,12 +38,14 @@ bool ThrottlingResourceHandler::OnRequestRedirected(int request_id,
   DCHECK(!cancelled_by_resource_throttle_);
 
   *defer = false;
-  while (index_ < throttles_.size()) {
-    throttles_[index_]->WillRedirectRequest(new_url, defer);
-    index_++;
+  while (next_index_ < throttles_.size()) {
+    int index = next_index_;
+    throttles_[index]->WillRedirectRequest(new_url, defer);
+    next_index_++;
     if (cancelled_by_resource_throttle_)
       return false;
     if (*defer) {
+      OnRequestDefered(index);
       deferred_stage_ = DEFERRED_REDIRECT;
       deferred_url_ = new_url;
       deferred_response_ = response;
@@ -46,7 +53,7 @@ bool ThrottlingResourceHandler::OnRequestRedirected(int request_id,
     }
   }
 
-  index_ = 0;  // Reset for next time.
+  next_index_ = 0;  // Reset for next time.
 
   return next_handler_->OnRequestRedirected(request_id, new_url, response,
                                             defer);
@@ -58,19 +65,21 @@ bool ThrottlingResourceHandler::OnWillStart(int request_id,
   DCHECK(!cancelled_by_resource_throttle_);
 
   *defer = false;
-  while (index_ < throttles_.size()) {
-    throttles_[index_]->WillStartRequest(defer);
-    index_++;
+  while (next_index_ < throttles_.size()) {
+    int index = next_index_;
+    throttles_[index]->WillStartRequest(defer);
+    next_index_++;
     if (cancelled_by_resource_throttle_)
       return false;
     if (*defer) {
+      OnRequestDefered(index);
       deferred_stage_ = DEFERRED_START;
       deferred_url_ = url;
       return true;  // Do not cancel.
     }
   }
 
-  index_ = 0;  // Reset for next time.
+  next_index_ = 0;  // Reset for next time.
 
   return next_handler_->OnWillStart(request_id, url, defer);
 }
@@ -80,19 +89,21 @@ bool ThrottlingResourceHandler::OnResponseStarted(int request_id,
                                                   bool* defer) {
   DCHECK(!cancelled_by_resource_throttle_);
 
-  while (index_ < throttles_.size()) {
-    throttles_[index_]->WillProcessResponse(defer);
-    index_++;
+  while (next_index_ < throttles_.size()) {
+    int index = next_index_;
+    throttles_[index]->WillProcessResponse(defer);
+    next_index_++;
     if (cancelled_by_resource_throttle_)
       return false;
     if (*defer) {
+      OnRequestDefered(index);
       deferred_stage_ = DEFERRED_RESPONSE;
       deferred_response_ = response;
       return true;  // Do not cancel.
     }
   }
 
-  index_ = 0;  // Reset for next time.
+  next_index_ = 0;  // Reset for next time.
 
   return next_handler_->OnResponseStarted(request_id, response, defer);
 }
@@ -117,6 +128,8 @@ void ThrottlingResourceHandler::Resume() {
 
   DeferredStage last_deferred_stage = deferred_stage_;
   deferred_stage_ = DEFERRED_NONE;
+  // Clear information about the throttle that delayed the request.
+  request()->LogUnblocked();
   switch (last_deferred_stage) {
     case DEFERRED_NONE:
       NOTREACHED();
@@ -177,4 +190,8 @@ void ThrottlingResourceHandler::ResumeResponse() {
   }
 }
 
+void ThrottlingResourceHandler::OnRequestDefered(int throttle_index) {
+  request()->LogBlockedBy(throttles_[throttle_index]->GetNameForLogging());
+}
+
 }  // namespace content