Fix DCHECK on net error page

DCHECK(committed_error_page_info_->auto_reload_triggered) was failing.
This is possible because when assigning a new value to
committed_error_page_info_, the auto load timer can still be active.

R=jianli

Bug: 881208
Change-Id: I361df3e17bef122f143331107a76d04487b32fea
Reviewed-on: https://chromium-review.googlesource.com/c/1240872Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Jian Li <jianli@chromium.org>
Commit-Queue: Dan H <harringtond@google.com>
Cr-Commit-Position: refs/heads/master@{#597183}

chrome/renderer/net/net_error_helper_core.cc

@@ -585,8 +585,13 @@ void NetErrorHelperCore::OnStartLoad(FrameType frame_type, PageType page_type) {
 
   // If there's no pending error page information associated with the page load,
   // or the new page is not an error page, then reset pending error page state.
-  if (!pending_error_page_info_ || page_type != ERROR_PAGE)
+  if (!pending_error_page_info_ || page_type != ERROR_PAGE) {
     CancelPendingFetches();
+  } else {
+    // Halt auto-reload if it's currently scheduled. OnFinishLoad will trigger
+    // auto-reload if appropriate.
+    PauseAutoReloadTimer();
+  }
 }
 
 void NetErrorHelperCore::OnCommitLoad(FrameType frame_type, const GURL& url) {

chrome/renderer/net/net_error_helper_core_unittest.cc

@@ -2114,6 +2114,27 @@ TEST_F(NetErrorHelperCoreAutoReloadTest, StopsOnOtherLoadStart) {
   EXPECT_EQ(0, core()->auto_reload_count());
 }
 
+// This is a regression test for http://crbug.com/881208.
+TEST_F(NetErrorHelperCoreAutoReloadTest, StopsOnErrorLoadCommit) {
+  DoErrorLoad(net::ERR_CONNECTION_RESET);
+  EXPECT_TRUE(timer()->IsRunning());
+
+  // Simulate manually reloading the error page while the timer is still
+  // running.
+  std::string html;
+  core()->PrepareErrorPage(
+      NetErrorHelperCore::MAIN_FRAME,
+      NetErrorForURL(net::ERR_CONNECTION_RESET, GURL(kFailedUrl)),
+      false /* is_failed_post */, false /* is_ignoring_cache */, &html);
+
+  core()->OnStartLoad(NetErrorHelperCore::MAIN_FRAME,
+                      NetErrorHelperCore::ERROR_PAGE);
+  EXPECT_FALSE(timer()->IsRunning());
+  core()->OnCommitLoad(NetErrorHelperCore::MAIN_FRAME, error_url());
+  core()->OnFinishLoad(NetErrorHelperCore::MAIN_FRAME);
+  EXPECT_TRUE(timer()->IsRunning());
+}
+
 TEST_F(NetErrorHelperCoreAutoReloadTest, ResetsCountOnSuccess) {
   DoErrorLoad(net::ERR_CONNECTION_RESET);
   base::TimeDelta delay = timer()->GetCurrentDelay();