Telemetry / Devtools TraceHandler: exposes tracing via dev tools.

content/browser/debugger/devtools_http_handler_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/debugger/devtools_http_handler_impl.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 290 matching lines @@
     BrowserThread::PostTask(
         BrowserThread::UI,
         FROM_HERE,
         base::Bind(&DevToolsHttpHandlerImpl::OnThumbnailRequestUI,
                    this,
                    connection_id,
                    info));
     return;
   }
 
+  if (info.path.find("/trace/") == 0) {
+    // Trace request.
+    BrowserThread::PostTask(
+        BrowserThread::UI,
+        FROM_HERE,
+        base::Bind(&DevToolsHttpHandlerImpl::OnTraceRequestUI,
+                   this,
+                   connection_id,
+                   info));
+    return;
+  }
+
   if (info.path == "" || info.path == "/") {
     // Discovery page request.
     BrowserThread::PostTask(
         BrowserThread::UI,
         FROM_HERE,
         base::Bind(&DevToolsHttpHandlerImpl::OnDiscoveryPageRequestUI,
                    this,
                    connection_id));
     return;
   }
@@ skipping 250 matching lines @@
   }
 
   std::string page_url = info.path.substr(prefix.length());
   std::string data = delegate_->GetPageThumbnailData(GURL(page_url));
   if (!data.empty())
     Send200(connection_id, data, "image/png");
   else
     Send404(connection_id);
 }
 
+void DevToolsHttpHandlerImpl::OnTraceRequestUI(
+    int connection_id,
+    const net::HttpServerRequestInfo& info) {
+  std::string prefix = "/trace/";
+  size_t pos = info.path.find(prefix);

[pfeldman, 2012/12/12 17:45:22]

This discovery handler is supposed to be used with the remote debugging
protocol. Tracing has nothing to do with the devtools at the moment. I would not
want this handler to become a collection of random instrumentations accessible
via web sockets.

+  if (pos != 0) {
+    Send404(connection_id);
+    return;
+  }
+
+  std::string command = info.path.substr(prefix.length());
+
+  std::string response("ok");
+  if (command == "start") {
+    // TODO(bulach): capture categories somehow.
+    std::string categories;
+    devtools_trace_handler_.BeginTracing(categories);
+  } else if (command == "stop")
+    devtools_trace_handler_.EndTracingAsync();
+  else if (command == "has_completed") {
+    response = devtools_trace_handler_.has_completed() ?
+        "ok" : "pending";
+  } else if (command == "get") {
+    if (devtools_trace_handler_.has_completed()) {
+      Send200(
+          connection_id, devtools_trace_handler_.GetAndResetTrace(),
+          "binary/octet-stream");
+      return;
+    }
+    Send404(connection_id);
+    return;
+  }
+  Send200(connection_id, response, "text/html; charset=UTF-8");
+}
+
 void DevToolsHttpHandlerImpl::OnDiscoveryPageRequestUI(int connection_id) {
   std::string response = delegate_->GetDiscoveryPageHTML();
   Send200(connection_id, response, "text/html; charset=UTF-8");
 }
 
 void DevToolsHttpHandlerImpl::OnWebSocketRequestUI(
     int connection_id,
     const net::HttpServerRequestInfo& request) {
   if (!thread_.get())
     return;
@@ skipping 234 matching lines @@
                                              page_info.id.c_str()));
     std::string devtools_frontend_url = GetFrontendURLInternal(
         page_info.id.c_str(),
         host);
     dictionary->SetString("devtoolsFrontendUrl", devtools_frontend_url);
   }
   return dictionary;
 }
 
 }  // namespace content