DevTools: execute scripts in addScriptToEvaluateOnLoad in order

Scripts added by addScriptToEvaluateOnLoad used to be evaluated
in the order of their addition.

This was regressed recently with https://crrev.com/578514.

R=caseq, pfeldman

Change-Id: Ieabd67aca497fab8eaff749fea0877d93c54deae
Reviewed-on: https://chromium-review.googlesource.com/1180585Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Andrey Lushnikov <lushnikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584293}

third_party/WebKit/LayoutTests/inspector-protocol/page/add-script-to-evaluate-on-load-expected.txt

+Tests that Page.addScriptToEvaluateOnLoad is executed in the order of addition
+message from 0
+message from 1
+message from 2
+message from 3
+message from 4
+message from 5
+message from 6
+message from 7
+message from 8
+message from 9
+message from 10
+message from 11
+message from 12
+message from 13
+message from 14
+

third_party/WebKit/LayoutTests/inspector-protocol/page/add-script-to-evaluate-on-load.js

+(async function(testRunner) {
+  const {page, session, dp} = await testRunner.startBlank(
+      'Tests that Page.addScriptToEvaluateOnLoad is executed in the order of addition');
+  dp.Runtime.enable();
+  dp.Page.enable();
+
+  dp.Runtime.onConsoleAPICalled(msg => testRunner.log(msg.params.args[0].value));
+
+  for (let i = 0; i < 15; ++i) {
+    await dp.Page.addScriptToEvaluateOnNewDocument({source: `
+      console.log('message from ${i}');
+    `});
+  }
+  await session.navigate('../resources/blank.html');
+  testRunner.completeTest();
+})

third_party/blink/renderer/core/inspector/inspector_page_agent.cc

@@ -444,7 +444,6 @@ InspectorPageAgent::InspectorPageAgent(
     : inspected_frames_(inspected_frames),
       v8_session_(v8_session),
       client_(client),
-      last_script_identifier_(0),
       reloading_(false),
       inspector_resource_content_loader_(resource_content_loader),
       resource_content_loader_client_id_(
@@ -542,13 +541,17 @@ Response InspectorPageAgent::disable() {
 
 Response InspectorPageAgent::addScriptToEvaluateOnLoad(const String& source,
                                                        String* identifier) {
-  // Assure we don't override existing ids -- m_lastScriptIdentifier could get
-  // out of sync WRT actual scripts once we restored the scripts from the cookie
-  // during navigation.
-  do {
-    *identifier = String::Number(++last_script_identifier_);
-  } while (!scripts_to_evaluate_on_load_.Get(*identifier).IsNull());
-  scripts_to_evaluate_on_load_.Set(*identifier, source);
+  std::vector<WTF::String> keys = scripts_to_evaluate_on_load_.Keys();
+  auto result = std::max_element(
+      keys.begin(), keys.end(), [](const WTF::String& a, const WTF::String& b) {
+        return Decimal::FromString(a) < Decimal::FromString(b);
+      });
+  if (result == keys.end()) {
+    scripts_to_evaluate_on_load_.Set(String::Number(1), source);
+  } else {
+    scripts_to_evaluate_on_load_.Set(
+        String::Number(Decimal::FromString(*result).ToDouble() + 1), source);
+  }
   return Response::OK();
 }
 
@@ -825,7 +828,13 @@ void InspectorPageAgent::DidNavigateWithinDocument(LocalFrame* frame) {
 void InspectorPageAgent::DidClearDocumentOfWindowObject(LocalFrame* frame) {
   if (!GetFrontend())
     return;
-  for (const WTF::String& key : scripts_to_evaluate_on_load_.Keys()) {
+  std::vector<WTF::String> keys = scripts_to_evaluate_on_load_.Keys();
+  std::sort(keys.begin(), keys.end(),
+            [](const WTF::String& a, const WTF::String& b) {
+              return Decimal::FromString(a) < Decimal::FromString(b);
+            });
+
+  for (const WTF::String& key : keys) {
     const WTF::String& script = scripts_to_evaluate_on_load_.Get(key);
     frame->GetScriptController().ExecuteScriptInMainWorld(script);
   }

third_party/blink/renderer/core/inspector/inspector_page_agent.h

@@ -237,7 +237,6 @@ class CORE_EXPORT InspectorPageAgent final
   HashMap<String, Vector<char>> compilation_cache_;
   v8_inspector::V8InspectorSession* v8_session_;
   Client* client_;
-  long last_script_identifier_;
   String pending_script_to_evaluate_on_load_once_;
   String script_to_evaluate_on_load_once_;
   bool reloading_;