[devtools] Clear issues upon committing a new page load

This prevents issues from the previous page from showing up in the
issues panel.

Bug: chromium:1057979
Change-Id: If2f61d9c8a402b30a41d4d9f83b9f356633eb5a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2164625
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#762435}

third_party/blink/renderer/core/page/page.cc

@@ -854,6 +854,7 @@ void Page::UpdateAcceleratedCompositingSettings() {
 void Page::DidCommitLoad(LocalFrame* frame) {
   if (main_frame_ == frame) {
     GetConsoleMessageStorage().Clear();
+    GetInspectorIssueStorage().Clear();
     // TODO(loonybear): Most of this doesn't appear to take into account that
     // each SVGImage gets it's own Page instance.
     GetDeprecation().ClearSuppression();

third_party/blink/web_tests/http/tests/inspector-protocol/audits/issues-cleared-on-load-commit-expected.txt

+Verifies that inspector issues do not persist through reloads.
+
+

third_party/blink/web_tests/http/tests/inspector-protocol/audits/issues-cleared-on-load-commit.js

+(async function(testRunner) {
+  const {page, session, dp} = await testRunner.startBlank(
+      `Verifies that inspector issues do not persist through reloads.\n`);
+
+  // Trigger a known issue, inspector-protocol/network/same-site-issue-blocked-cookie-not-secure.js ensures this
+  // issue is actually triggered.
+  const setCookieUrl = 'https://cookie.test:8443/inspector-protocol/network/resources/set-cookie.php?cookie='
+  + encodeURIComponent('name=value; SameSite=None');
+  await session.evaluateAsync(`fetch('${setCookieUrl}', {method: 'POST', credentials: 'include'})`);
+
+  // Reloading the page should clear the issue.
+  await dp.Page.reload();
+
+  // This should never be printed.
+  dp.Audits.onIssueAdded(() => testRunner.log(`Issue should have been cleared by the reload`));
+  await dp.Audits.enable();
+
+  testRunner.completeTest();
+})