[inspector] Send empty string for `Debugger.CallFrame.url`.

This is the final step towards moving away from sending `url` with
every call frame when emitting the `Debugger.paused` event.

Fixed: chromium:1270316
Bug: chromium:1271078
Change-Id: I87a286d81eb91a9bed64213c4b18db0675858822
Doc: https://bit.ly/devtools-debugger-callframe-url
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3345001
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78974}

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

@@ -1466,20 +1466,13 @@ Response V8DebuggerAgentImpl::currentCallFrames(
             .setLineNumber(loc.GetLineNumber())
             .setColumnNumber(loc.GetColumnNumber())
             .build();
-    String16 scriptId = String16::fromInteger(script->Id());
-    ScriptsMap::iterator scriptIterator =
-        m_scripts.find(location->getScriptId());
-    String16 url;
-    if (scriptIterator != m_scripts.end()) {
-      url = scriptIterator->second->sourceURL();
-    }
 
     auto frame = CallFrame::create()
                      .setCallFrameId(callFrameId)
                      .setFunctionName(toProtocolString(
                          m_isolate, iterator->GetFunctionDebugName()))
                      .setLocation(std::move(location))
-                     .setUrl(url)
+                     .setUrl(String16())
                      .setScopeChain(std::move(scopes))
                      .setThis(std::move(protocolReceiver))
                      .build();

test/inspector/debugger/call-frame-url-expected.txt

@@ -4,12 +4,12 @@ Tests url in Debugger.CallFrame.
         url : 
     }
     [1] : {
-        url : source-url.js
+        url : 
     }
     [2] : {
-        url : test.js
+        url : 
     }
     [3] : {
-        url : expr.js
+        url : 
     }
 ]

test/inspector/debugger/resource-name-to-url-expected.txt

@@ -124,7 +124,7 @@ Test runtime stack trace:
 }
 Test debugger stack trace:
 [
-    [0] : prefix://url
-    [1] : boo.js
-    [2] : prefix://url
+    [0] : 
+    [1] : 
+    [2] : 
 ]

test/inspector/runtime/es6-module-expected.txt

@@ -123,7 +123,7 @@ console.log(239)
                 this : {
                     type : undefined
                 }
-                url : module3
+                url : 
             }
         ]
         hitBreakpoints : [