Update OnCommit to return ObservePolicy.

chrome/browser/page_load_metrics/metrics_web_contents_observer.cc

 // Copyright 2015 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/page_load_metrics/metrics_web_contents_observer.h"
 
 #include <algorithm>
 #include <ostream>
 #include <string>
 #include <utility>
@@ skipping 15 matching lines @@
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_message_macros.h"
 #include "ui/base/page_transition_types.h"
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(
     page_load_metrics::MetricsWebContentsObserver);
 
+// This macro invokes the specified method on each observer, passing the
+// variable length arguments as the method's arguments, and removes the observer
+// from the list of observers if the given method returns STOP_OBSERVING.
+#define INVOKE_AND_PRUNE_OBSERVERS(observers, Method, ...)    \
+  for (auto it = observers.begin(); it != observers.end();) { \
+    if ((*it)->Method(__VA_ARGS__) ==                         \
+        PageLoadMetricsObserver::STOP_OBSERVING) {            \
+      it = observers.erase(it);                               \
+    } else {                                                  \
+      ++it;                                                   \
+    }                                                         \
+  }
+
 namespace page_load_metrics {
 
 namespace internal {
 
 const char kErrorEvents[] = "PageLoad.Internal.ErrorCode";
 const char kAbortChainSizeReload[] =
     "PageLoad.Internal.ProvisionalAbortChainSize.Reload";
 const char kAbortChainSizeForwardBack[] =
     "PageLoad.Internal.ProvisionalAbortChainSize.ForwardBack";
 const char kAbortChainSizeNewNavigation[] =
@@ skipping 389 matching lines @@
 
 void PageLoadTracker::Commit(content::NavigationHandle* navigation_handle) {
   // TODO(bmcquade): To improve accuracy, consider adding commit time to
   // NavigationHandle. Taking a timestamp here should be close enough for now.
   commit_time_ = base::TimeTicks::Now();
   ClampBrowserTimestampIfInterProcessTimeTickSkew(&commit_time_);
   url_ = navigation_handle->GetURL();
   // Some transitions (like CLIENT_REDIRECT) are only known at commit time.
   page_transition_ = navigation_handle->GetPageTransition();
   user_gesture_ = navigation_handle->HasUserGesture();
-  for (const auto& observer : observers_) {
-    observer->OnCommit(navigation_handle);
-  }
+
+  INVOKE_AND_PRUNE_OBSERVERS(observers_, OnCommit, navigation_handle);
   LogAbortChainHistograms(navigation_handle);
 }
 
 void PageLoadTracker::FailedProvisionalLoad(
     content::NavigationHandle* navigation_handle) {
   DCHECK(!failed_provisional_load_info_);
   failed_provisional_load_info_.reset(new FailedProvisionalLoadInfo(
       base::TimeTicks::Now() - navigation_handle->NavigationStart(),
       navigation_handle->GetNetErrorCode()));
 }
@@ skipping 10 matching lines @@
   }
 }
 
 void PageLoadTracker::FlushMetricsOnAppEnterBackground() {
   if (!app_entered_background_) {
     RecordAppBackgroundPageLoadCompleted(false);
     app_entered_background_ = true;
   }
 
   const PageLoadExtraInfo info = ComputePageLoadExtraInfo();
-  for (auto it = observers_.begin(); it != observers_.end();) {
-    if ((*it)->FlushMetricsOnAppEnterBackground(timing_, info) ==
-        PageLoadMetricsObserver::STOP_OBSERVING) {
-      it = observers_.erase(it);
-    } else {
-      ++it;
-    }
-  }
+  INVOKE_AND_PRUNE_OBSERVERS(observers_, FlushMetricsOnAppEnterBackground,
+                             timing_, info);
 }
 
 void PageLoadTracker::NotifyClientRedirectTo(
     const PageLoadTracker& destination) {
   if (timing_.first_paint) {
     base::TimeTicks first_paint_time =
         navigation_start() + timing_.first_paint.value();
     base::TimeDelta first_paint_to_navigation;
     if (destination.navigation_start() > first_paint_time)
       first_paint_to_navigation =
@@ skipping 592 matching lines @@
     content::NavigationHandle* navigation_handle) const {
   DCHECK(navigation_handle->IsInMainFrame());
   DCHECK(!navigation_handle->HasCommitted() ||
          !navigation_handle->IsSamePage());
 
   return BrowserPageTrackDecider(embedder_interface_.get(), web_contents(),
                                  navigation_handle).ShouldTrack();
 }
 
 }  // namespace page_load_metrics