[Backport] Security bug 1202534

Cherry-pick of patch originally reviewed on
https://chromium-review.googlesource.com/c/v8/v8/+/2940882:
M86-LTS: [debugger] Return ServerError if debugger agent is disabled

This returns a server error on setting breakpoints if the
agent is disabled.

(cherry picked from commit 5aa2de8128f885c44df79d38fb4aa5c6a5d94306)

Also-by: bmeurer@chromium.org
Fixed: chromium:1202534
No-Try: true
No-Presubmit: true
No-Tree-Checks: true
Change-Id: I87c80a4bd785fa5c59a8dd0d5ac5f4b31b015ed8
Commit-Queue: Kim-Anh Tran <kimanh@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Auto-Submit: Kim-Anh Tran <kimanh@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#74399}
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Commit-Queue: Artem Sumaneev <asumaneev@google.com>
Cr-Commit-Position: refs/branch-heads/8.6@{#105}
Cr-Branched-From: a64aed2333abf49e494d2a5ce24bbd14fff19f60-refs/heads/8.6.395@{#1}
Cr-Branched-From: a626bc036236c9bf92ac7b87dc40c9e538b087e3-refs/heads/master@{#69472}
Reviewed-by: Michal Klocek <michal.klocek@qt.io>

Author: ktran

chromium/v8/src/inspector/v8-debugger-agent-impl.cc

@@ -499,6 +499,8 @@ Response V8DebuggerAgentImpl::setBreakpointByUrl(
     Maybe<int> optionalColumnNumber, Maybe<String16> optionalCondition,
     String16* outBreakpointId,
     std::unique_ptr<protocol::Array<protocol::Debugger::Location>>* locations) {
+  if (!enabled()) return Response::ServerError(kDebuggerNotEnabled);
+
   *locations = std::make_unique<Array<protocol::Debugger::Location>>();
 
   int specified = (optionalURL.isJust() ? 1 : 0) +
@@ -587,6 +589,8 @@ Response V8DebuggerAgentImpl::setBreakpoint(
   String16 breakpointId = generateBreakpointId(
       BreakpointType::kByScriptId, location->getScriptId(),
       location->getLineNumber(), location->getColumnNumber(0));
+  if (!enabled()) return Response::ServerError(kDebuggerNotEnabled);
+
   if (m_breakpointIdToDebuggerBreakpointIds.find(breakpointId) !=
       m_breakpointIdToDebuggerBreakpointIds.end()) {
     return Response::ServerError(
@@ -605,6 +609,8 @@ Response V8DebuggerAgentImpl::setBreakpoint(
 Response V8DebuggerAgentImpl::setBreakpointOnFunctionCall(
     const String16& functionObjectId, Maybe<String16> optionalCondition,
     String16* outBreakpointId) {
+  if (!enabled()) return Response::ServerError(kDebuggerNotEnabled);
+
   InjectedScript::ObjectScope scope(m_session, functionObjectId);
   Response response = scope.initialize();
   if (!response.IsSuccess()) return response;