Revert of Add additional auditing for PageLoadTiming. (patchset #7 id:120001 of https://codereview.chromium.org/1735363002/ )

Reason for revert:
Cause flakiness on all GPU debug bots

stack trace:

0   libbase.dylib                       0x000000011b89dbaf _ZN4base5debug10StackTraceC2Ev + 47
1   libbase.dylib                       0x000000011b89dd53 _ZN4base5debug10StackTraceC1Ev + 35
2   libbase.dylib                       0x000000011b929c70 _ZN7logging10LogMessageD2Ev + 80
3   libbase.dylib                       0x000000011b9275a3 _ZN7logging10LogMessageD1Ev + 35
4   libchrome_main_dll.dylib            0x000000010f3e0985 _ZN17page_load_metrics12_GLOBAL__N_121IsValidPageLoadTimingERKNS_14PageLoadTimingE + 2389
5   libchrome_main_dll.dylib            0x000000010f3dffba _ZN17page_load_metrics15PageLoadTracker12UpdateTimingERKNS_14PageLoadTimingE + 122
6   libchrome_main_dll.dylib            0x000000010f3e24c3 _ZN17page_load_metrics26MetricsWebContentsObserver15OnTimingUpdatedEPN7content15RenderFrameHostERKNS_14PageLoadTimingE + 275
7   libchrome_main_dll.dylib            0x000000010f3e8564 _ZN3IPC20DispatchToMethodImplIN17page_load_metrics26MetricsWebContentsObserverEMS2_FvPN7content15RenderFrameHostERKNS1_14PageLoadTimingEES4_NSt3__15tupleIJS6_EEEJLm0EEEEvPT_T0_PT1_RKT2_N4base13IndexSequenceIJXspT3_EEEE + 164
8   libchrome_main_dll.dylib            0x000000010f3e8446 _ZN3IPC16DispatchToMethodIN17page_load_metrics26MetricsWebContentsObserverEN7content15RenderFrameHostEJRKNS1_14PageLoadTimingEEJS5_EEENSt3__19enable_ifIXeqsZT1_sZT2_EvE4typeEPT_MSC_FvPT0_DpT1_ESF_RKNS8_5tupleIJDpT2_EEE + 102
9   libchrome_main_dll.dylib            0x000000010f3e2348 _ZN3IPC8MessageTI37PageLoadMetricsMsg_TimingUpdated_MetaNSt3__15tupleIJN17page_load_metrics14PageLoadTimingEEEEvE8DispatchINS4_26MetricsWebContentsObserverES9_N7content15RenderFrameHostEMS9_FvPSB_RKS5_EEEbPKNS_7MessageEPT_PT0_PT1_T2_ + 248
10  libchrome_main_dll.dylib            0x000000010f3e21eb _ZN17page_load_metrics26MetricsWebContentsObserver17OnMessageReceivedERKN3IPC7MessageEPN7content15RenderFrameHostE + 555
11  libcontent.dylib                    0x000000012435be4b _ZN7content15WebContentsImpl17OnMessageReceivedEPNS_14RenderViewHostEPNS_15RenderFrameHostERKN3IPC7MessageE + 475
12  libcontent.dylib                    0x000000012437fc42 _ZN7content15WebContentsImpl17OnMessageReceivedEPNS_15RenderFrameHostERKN3IPC7MessageE + 66
13  libcontent.dylib                    0x000000012437fcaa _ZThn128_N7content15WebContentsImpl17OnMessageReceivedEPNS_15RenderFrameHostERKN3IPC7MessageE + 58
14  libcontent.dylib                    0x00000001237a87cf _ZN7content19RenderFrameHostImpl17OnMessageReceivedERKN3IPC7MessageE + 591
15  libcontent.dylib                    0x0000000123f03603 _ZN7content21RenderProcessHostImpl17OnMessageReceivedERKN3IPC7MessageE + 2179
16  libcontent.dylib                    0x0000000123f046b2 _ZThn8_N7content21RenderProcessHostImpl17OnMessageReceivedERKN3IPC7MessageE + 50
17  libipc.dylib                        0x000000012d8b753e _ZN3IPC12ChannelProxy7Context17OnDispatchMessageERKNS_7MessageE + 750
18  libipc.dylib                        0x000000012d8bdfa7 _ZN4base8internal15RunnableAdapterIMN3IPC12ChannelProxy7ContextEFvRKNS2_7MessageEEE3RunIJS7_EEEvPS4_DpOT_ + 135
19  libipc.dylib                        0x000000012d8bde6d _ZN4base8internal12InvokeHelperILb0EvNS0_15RunnableAdapterIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEEEE8MakeItSoIJPS5_S8_EEEvSB_DpOT_ + 77
20  libipc.dylib                        0x000000012d8bddfc _ZN4base8internal7InvokerINS_13IndexSequenceIJLm0ELm1EEEENS0_9BindStateINS0_15RunnableAdapterIMN3IPC12ChannelProxy7ContextEFvRKNS6_7MessageEEEEFvPS8_SB_EJSF_SB_EEENS0_12InvokeHelperILb0EvSE_EEFvvEE3RunEPNS0_13BindStateBaseE + 140
21  libbase.dylib                       0x000000011b8747ff _ZNK4base8CallbackIFvvEE3RunEv + 63
22  libbase.dylib                       0x000000011b89f91e _ZN4base5debug13TaskAnnotator7RunTaskEPKcRKNS_11PendingTaskE + 654
23  libbase.dylib                       0x000000011b96f350 _ZN4base11MessageLoop7RunTaskERKNS_11PendingTaskE + 848
24  libbase.dylib                       0x000000011b96f986 _ZN4base11MessageLoop21DeferOrRunPendingTaskERKNS_11PendingTaskE + 86
25  libbase.dylib                       0x000000011b97000e _ZN4base11MessageLoop6DoWorkEv + 526
26  libbase.dylib                       0x000000011b849ae8 _ZN4base24MessagePumpCFRunLoopBase7RunWorkEv + 104
27  libbase.dylib                       0x000000011b849a5a ___ZN4base24MessagePumpCFRunLoopBase13RunWorkSourceEPv_block_invoke + 42
28  libbase.dylib                       0x000000011b92d35a _ZN4base3mac15CallWithEHFrameEU13block_pointerFvvE + 10
29  libbase.dylib                       0x000000011b848df5 _ZN4base24MessagePumpCFRunLoopBase13RunWorkSourceEPv + 101
30  CoreFoundation                      0x00007fff9256fa01 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
31  CoreFoundation                      0x00007fff92561b8d __CFRunLoopDoSources0 + 269
32  CoreFoundation                      0x00007fff925611bf __CFRunLoopRun + 927
33  CoreFoundation                      0x00007fff92560bd8 CFRunLoopRunSpecific + 296
34  HIToolbox                           0x00007fff8fb7d56f RunCurrentEventLoopInMode + 235
35  HIToolbox                           0x00007fff8fb7d2ea ReceiveNextEventCommon + 431
36  HIToolbox                           0x00007fff8fb7d12b _BlockUntilNextEventMatchingListInModeWithFilter + 71
37  AppKit                              0x00007fff8af9f8ab _DPSNextEvent + 978
38  AppKit                              0x00007fff8af9ee58 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 346
39  AppKit                              0x00007fff8af94af3 -[NSApplication run] + 594
40  libbase.dylib                       0x000000011b84ae02 _ZN4base24MessagePumpNSApplication5DoRunEPNS_11MessagePump8DelegateE + 306
41  libbase.dylib                       0x000000011b8496fd _ZN4base24MessagePumpCFRunLoopBase3RunEPNS_11MessagePump8DelegateE + 125
42  libbase.dylib                       0x000000011b96eb93 _ZN4base11MessageLoop10RunHandlerEv + 275
43  libbase.dylib                       0x000000011ba01855 _ZN4base7RunLoop3RunEv + 85
44  libchrome_main_dll.dylib            0x000000010b60bfc0 _ZN22ChromeBrowserMainParts18MainMessageLoopRunEPi + 400
45  libcontent.dylib                    0x00000001233448c7 _ZN7content15BrowserMainLoop23RunMainMessageLoopPartsEv + 359
46  libcontent.dylib                    0x0000000123352e4f _ZN7content21BrowserMainRunnerImpl3RunEv + 447
47  libcontent.dylib                    0x000000012333c1cc _ZN7content11BrowserMainERKNS_18MainFunctionParamsE + 348
48  libcontent.dylib                    0x000000012303b217 _ZN7content23RunNamedProcessTypeMainERKNSt3__112basic_stringIcNS0_11char_traitsIcEENS0_9allocatorIcEEEERKNS_18MainFunctionParamsEPNS_19ContentMainDelegateE + 599
49  libcontent.dylib                    0x000000012303cfa1 _ZN7content21ContentMainRunnerImpl3RunEv + 577
50  libcontent.dylib                    0x000000012303a460 _ZN7content11ContentMainERKNS_17ContentMainParamsE + 144
51  libchrome_main_dll.dylib            0x000000010b2caed3 ChromeMain + 83
52  Chromium                            0x000000010b256fef main + 783
53  Chromium                            0x000000010b256cd4 start + 52
54  ???                                 0x0000000000000017 0x0 + 23

Original issue's description:
> Add additional auditing for PageLoadTiming.
>
> BUG=589944
>
> Committed: https://crrev.com/a562015fd6f1cea8a2f91c994d1024bc8f5ce066
> Cr-Commit-Position: refs/heads/master@{#378009}

TBR=csharrison@chromium.org,bmcquade@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=589944

Review URL: https://codereview.chromium.org/1743923002

Cr-Commit-Position: refs/heads/master@{#378093}

7 files changed, 16 insertions, 125 deletions

diff --git a/chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc b/chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc
index 67959ce..039b93d 100644
--- a/chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc
+++ b/chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc
@@ -147,7 +147,6 @@ TEST_F(AbortsPageLoadMetricsObserverTest, NoAbortNewNavigationAfterPaint) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_paint = base::TimeDelta::FromMicroseconds(1);
-  PopulateRequiredTimingFields(&timing);
   NavigateAndCommit(GURL("https://www.google.com"));
   SimulateTimingUpdate(timing);
   NavigateAndCommit(GURL("https://www.example.com"));
diff --git a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
index 1ffa417..7ef0dc1 100644
--- a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
+++ b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
@@ -49,7 +49,6 @@ TEST_F(CorePageLoadMetricsObserverTest, SamePageNoTriggerUntilTrueNavCommit) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_layout = first_layout;
-  PopulateRequiredTimingFields(&timing);
 
   NavigateAndCommit(GURL(kDefaultTestUrl));
   SimulateTimingUpdate(timing);
@@ -76,7 +75,6 @@ TEST_F(CorePageLoadMetricsObserverTest, SingleMetricAfterCommit) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_layout = first_layout;
-  PopulateRequiredTimingFields(&timing);
 
   NavigateAndCommit(GURL(kDefaultTestUrl));
   SimulateTimingUpdate(timing);
@@ -96,7 +94,7 @@ TEST_F(CorePageLoadMetricsObserverTest, SingleMetricAfterCommit) {
 }
 
 TEST_F(CorePageLoadMetricsObserverTest, MultipleMetricsAfterCommits) {
-  base::TimeDelta first_layout_1 = base::TimeDelta::FromMilliseconds(10);
+  base::TimeDelta first_layout_1 = base::TimeDelta::FromMilliseconds(1);
   base::TimeDelta first_layout_2 = base::TimeDelta::FromMilliseconds(20);
   base::TimeDelta response = base::TimeDelta::FromMilliseconds(10);
   base::TimeDelta first_text_paint = base::TimeDelta::FromMilliseconds(30);
@@ -110,7 +108,6 @@ TEST_F(CorePageLoadMetricsObserverTest, MultipleMetricsAfterCommits) {
   timing.first_text_paint = first_text_paint;
   timing.dom_content_loaded_event_start = dom_content;
   timing.load_event_start = load;
-  PopulateRequiredTimingFields(&timing);
 
   NavigateAndCommit(GURL(kDefaultTestUrl));
   SimulateTimingUpdate(timing);
@@ -120,7 +117,6 @@ TEST_F(CorePageLoadMetricsObserverTest, MultipleMetricsAfterCommits) {
   page_load_metrics::PageLoadTiming timing2;
   timing2.navigation_start = base::Time::FromDoubleT(200);
   timing2.first_layout = first_layout_2;
-  PopulateRequiredTimingFields(&timing2);
 
   SimulateTimingUpdate(timing2);
 
@@ -154,7 +150,6 @@ TEST_F(CorePageLoadMetricsObserverTest, BackgroundDifferentHistogram) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_layout = first_layout;
-  PopulateRequiredTimingFields(&timing);
 
   // Simulate "Open link in new tab."
   web_contents()->WasHidden();
@@ -203,7 +198,6 @@ TEST_F(CorePageLoadMetricsObserverTest, OnlyBackgroundLaterEvents) {
   web_contents()->WasShown();
   timing.first_layout = base::TimeDelta::FromSeconds(3);
   timing.first_text_paint = base::TimeDelta::FromSeconds(4);
-  PopulateRequiredTimingFields(&timing);
   SimulateTimingUpdate(timing);
 
   // Navigate again to force histogram recording.
@@ -242,7 +236,6 @@ TEST_F(CorePageLoadMetricsObserverTest, DontBackgroundQuickerLoad) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_layout = first_layout;
-  PopulateRequiredTimingFields(&timing);
 
   web_contents()->WasHidden();
 
@@ -308,7 +301,6 @@ TEST_F(CorePageLoadMetricsObserverTest, BackgroundBeforePaint) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_paint = base::TimeDelta::FromSeconds(10);
-  PopulateRequiredTimingFields(&timing);
   NavigateAndCommit(GURL(kDefaultTestUrl));
   // Background the tab and go for a coffee or something.
   web_contents()->WasHidden();
@@ -332,7 +324,6 @@ TEST_F(CorePageLoadMetricsObserverTest, RapporLongPageLoad) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_contentful_paint = base::TimeDelta::FromSeconds(40);
-  PopulateRequiredTimingFields(&timing);
   NavigateAndCommit(GURL(kDefaultTestUrl));
   SimulateTimingUpdate(timing);
 
@@ -355,7 +346,6 @@ TEST_F(CorePageLoadMetricsObserverTest, RapporQuickPageLoad) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_contentful_paint = base::TimeDelta::FromSeconds(1);
-  PopulateRequiredTimingFields(&timing);
 
   NavigateAndCommit(GURL(kDefaultTestUrl));
   SimulateTimingUpdate(timing);
diff --git a/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc b/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc
index ae25b65..ac68b5f 100644
--- a/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc
+++ b/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc
@@ -53,7 +53,6 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, NoReferral) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_text_paint = base::TimeDelta::FromMilliseconds(1);
-  PopulateRequiredTimingFields(&timing);
   NavigateAndCommit(GURL("http://www.example.com"));
 
   SimulateTimingUpdate(timing);
@@ -67,7 +66,6 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, ReferralsFromGWSHTTPToHTTPS) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_text_paint = base::TimeDelta::FromMilliseconds(1);
-  PopulateRequiredTimingFields(&timing);
   // HTTPS google.com referral  to HTTP example.com.
   set_referrer(content::Referrer(GURL("https://www.google.com"),
                                  blink::WebReferrerPolicyOrigin));
@@ -87,7 +85,6 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, ReferralFromGWS) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_text_paint = base::TimeDelta::FromMilliseconds(1);
-  PopulateRequiredTimingFields(&timing);
 
   set_referrer(content::Referrer(GURL("https://www.google.com/url"),
                                  blink::WebReferrerPolicyDefault));
@@ -107,7 +104,6 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, ReferralFromGWSBackgroundLater) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_text_paint = base::TimeDelta::FromMicroseconds(1);
-  PopulateRequiredTimingFields(&timing);
 
   set_referrer(content::Referrer(GURL("https://www.google.com/url"),
                                  blink::WebReferrerPolicyDefault));
@@ -128,7 +124,6 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, ReferralsFromCaseInsensitive) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_text_paint = base::TimeDelta::FromMilliseconds(1);
-  PopulateRequiredTimingFields(&timing);
   // HTTPS google.com referral  to HTTP example.com.
   set_referrer(content::Referrer(GURL("https://wWw.GoOGlE.cOm/webhp"),
                                  blink::WebReferrerPolicyOrigin));
@@ -147,7 +142,6 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, ReferralsFromGWSOrigin) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_text_paint = base::TimeDelta::FromMilliseconds(1);
-  PopulateRequiredTimingFields(&timing);
   // HTTPS google.com referral  to HTTP example.com.
   set_referrer(content::Referrer(GURL("https://www.google.com"),
                                  blink::WebReferrerPolicyOrigin));
@@ -158,7 +152,6 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, ReferralsFromGWSOrigin) {
   page_load_metrics::PageLoadTiming timing2;
   timing2.navigation_start = base::Time::FromDoubleT(10);
   timing2.first_text_paint = base::TimeDelta::FromMilliseconds(100);
-  PopulateRequiredTimingFields(&timing2);
   // HTTPS google.com referral  to HTTP example.com.
   set_referrer(content::Referrer(GURL("https://www.google.co.in"),
                                  blink::WebReferrerPolicyOrigin));
@@ -180,7 +173,6 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, ReferralNotFromGWS) {
   page_load_metrics::PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
   timing.first_text_paint = base::TimeDelta::FromMilliseconds(1);
-  PopulateRequiredTimingFields(&timing);
   set_referrer(content::Referrer(GURL("https://www.anothersite.com"),
                                  blink::WebReferrerPolicyDefault));
   NavigateAndCommit(GURL("https://www.example.com"));
diff --git a/chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.cc b/chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.cc
index e7d2656..44ff512 100644
--- a/chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.cc
+++ b/chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.cc
@@ -42,40 +42,6 @@ PageLoadMetricsObserverTestHarness::PageLoadMetricsObserverTestHarness()
 
 PageLoadMetricsObserverTestHarness::~PageLoadMetricsObserverTestHarness() {}
 
-// static
-void PageLoadMetricsObserverTestHarness::PopulateRequiredTimingFields(
-    PageLoadTiming* inout_timing) {
-  if (!inout_timing->first_contentful_paint.is_zero() &&
-      inout_timing->first_paint.is_zero()) {
-    inout_timing->first_paint = inout_timing->first_contentful_paint;
-  }
-  if (!inout_timing->first_text_paint.is_zero() &&
-      inout_timing->first_paint.is_zero()) {
-    inout_timing->first_paint = inout_timing->first_text_paint;
-  }
-  if (!inout_timing->first_image_paint.is_zero() &&
-      inout_timing->first_paint.is_zero()) {
-    inout_timing->first_paint = inout_timing->first_image_paint;
-  }
-  if (!inout_timing->first_paint.is_zero() &&
-      inout_timing->first_layout.is_zero()) {
-    inout_timing->first_layout = inout_timing->first_paint;
-  }
-  if (!inout_timing->load_event_start.is_zero() &&
-      inout_timing->dom_content_loaded_event_start.is_zero()) {
-    inout_timing->dom_content_loaded_event_start =
-        inout_timing->load_event_start;
-  }
-  if (!inout_timing->first_layout.is_zero() &&
-      inout_timing->response_start.is_zero()) {
-    inout_timing->response_start = inout_timing->first_layout;
-  }
-  if (!inout_timing->dom_content_loaded_event_start.is_zero() &&
-      inout_timing->response_start.is_zero()) {
-    inout_timing->response_start = inout_timing->dom_content_loaded_event_start;
-  }
-}
-
 void PageLoadMetricsObserverTestHarness::SetUp() {
   ChromeRenderViewHostTestHarness::SetUp();
   SetContents(CreateTestWebContents());
diff --git a/chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h b/chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h
index ddbeb25..56e0832 100644
--- a/chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h
+++ b/chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h
@@ -22,10 +22,6 @@ class PageLoadMetricsObserverTestHarness
   PageLoadMetricsObserverTestHarness();
   ~PageLoadMetricsObserverTestHarness() override;
 
-  // Helper that fills in any timing fields that MWCO requires but that are
-  // currently missing.
-  static void PopulateRequiredTimingFields(PageLoadTiming* inout_timing);
-
   void SetUp() override;
 
   virtual void RegisterObservers(PageLoadTracker* tracker) {}
diff --git a/components/page_load_metrics/browser/metrics_web_contents_observer.cc b/components/page_load_metrics/browser/metrics_web_contents_observer.cc
index 146013d..21130fa 100644
--- a/components/page_load_metrics/browser/metrics_web_contents_observer.cc
+++ b/components/page_load_metrics/browser/metrics_web_contents_observer.cc
@@ -46,78 +46,31 @@ bool IsRelevantNavigation(content::NavigationHandle* navigation_handle,
          (mime_type == "text/html" || mime_type == "application/xhtml+xml");
 }
 
-// If second is non-zero, first must also be non-zero and less than or equal to
-// second.
-bool EventsInOrder(base::TimeDelta first, base::TimeDelta second) {
-  if (second.is_zero()) {
-    return true;
-  }
-  return !first.is_zero() && first <= second;
-}
-
 bool IsValidPageLoadTiming(const PageLoadTiming& timing) {
   if (timing.IsEmpty())
     return false;
 
   // If we have a non-empty timing, it should always have a navigation start.
   if (timing.navigation_start.is_null()) {
-    DLOG(FATAL) << "Received null navigation_start.";
-    return false;
-  }
-
-  // Verify proper ordering between the various timings.
-
-  if (!EventsInOrder(timing.response_start,
-                     timing.dom_content_loaded_event_start)) {
-    // We sometimes get a zero response_start with a non-zero DCL. See
-    // crbug.com/590212.
-    DLOG(ERROR) << "Invalid response_start " << timing.response_start
-                << " for dom_content_loaded_event_start "
-                << timing.dom_content_loaded_event_start;
-    return false;
-  }
-
-  if (!EventsInOrder(timing.dom_content_loaded_event_start,
-                     timing.load_event_start)) {
-    // TODO(csharrison) crbug.com/536203 shows that sometimes we can get a load
-    // event without a DCL. Figure out if we can change this condition to use a
-    // DLOG(FATAL) in the condition.
-    DLOG(ERROR) << "Invalid dom_content_loaded_event_start "
-                << timing.dom_content_loaded_event_start
-                << " for load_event_start " << timing.load_event_start;
-    return false;
-  }
-
-  if (!EventsInOrder(timing.response_start, timing.first_layout)) {
-    // We sometimes get a zero response_start with a non-zero first layout. See
-    // crbug.com/590212.
-    DLOG(ERROR) << "Invalid response_start " << timing.response_start
-                << " for first_layout " << timing.first_layout;
-    return false;
-  }
-
-  if (!EventsInOrder(timing.first_layout, timing.first_paint)) {
-    DLOG(FATAL) << "Invalid first_layout " << timing.first_layout
-                << " for first_paint " << timing.first_paint;
-    return false;
-  }
-
-  if (!EventsInOrder(timing.first_paint, timing.first_text_paint)) {
-    DLOG(FATAL) << "Invalid first_paint " << timing.first_paint
-                << " for first_text_paint " << timing.first_text_paint;
+    NOTREACHED();
     return false;
   }
 
-  if (!EventsInOrder(timing.first_paint, timing.first_image_paint)) {
-    DLOG(FATAL) << "Invalid first_paint " << timing.first_paint
-                << " for first_image_paint " << timing.first_image_paint;
+  // If we have a DOM content loaded event, we should have a response start.
+  if (!timing.dom_content_loaded_event_start.is_zero() &&
+      timing.response_start > timing.dom_content_loaded_event_start) {
+    NOTREACHED();
     return false;
   }
 
-  if (!EventsInOrder(timing.first_paint, timing.first_contentful_paint)) {
-    DLOG(FATAL) << "Invalid first_paint " << timing.first_paint
-                << " for first_contentful_paint "
-                << timing.first_contentful_paint;
+  // If we have a load event, we should have both a response start and a DCL.
+  // TODO(csharrison) crbug.com/536203 shows that sometimes we can get a load
+  // event without a DCL. Figure out if we can change this condition to use a
+  // NOTREACHED in the condition.
+  if (!timing.load_event_start.is_zero() &&
+      (timing.dom_content_loaded_event_start.is_zero() ||
+       timing.response_start > timing.load_event_start ||
+       timing.dom_content_loaded_event_start > timing.load_event_start)) {
     return false;
   }
 
@@ -135,9 +88,7 @@ UserAbortType AbortTypeForPageTransition(ui::PageTransition transition) {
     return ABORT_FORWARD_BACK;
   if (ui::PageTransitionIsNewNavigation(transition))
     return ABORT_NEW_NAVIGATION;
-  DLOG(FATAL)
-      << "AbortTypeForPageTransition received unexpected ui::PageTransition: "
-      << transition;
+  NOTREACHED();
   return ABORT_OTHER;
 }
 
@@ -201,9 +152,7 @@ void PageLoadTracker::LogAbortChainHistograms(
                            aborted_chain_size_);
       return;
     default:
-      DLOG(FATAL)
-          << "LogAbortChainHistograms received unexpected ui::PageTransition: "
-          << committed_transition;
+      NOTREACHED();
       return;
   }
 }
diff --git a/components/page_load_metrics/browser/metrics_web_contents_observer_unittest.cc b/components/page_load_metrics/browser/metrics_web_contents_observer_unittest.cc
index 7c3af90..975bb97 100644
--- a/components/page_load_metrics/browser/metrics_web_contents_observer_unittest.cc
+++ b/components/page_load_metrics/browser/metrics_web_contents_observer_unittest.cc
@@ -153,7 +153,6 @@ TEST_F(MetricsWebContentsObserverTest, SamePageNoTrigger) {
 
   PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);
-  timing.response_start = base::TimeDelta::FromMilliseconds(1);
   timing.first_layout = first_layout;
 
   content::WebContentsTester* web_contents_tester =