DevTools: speed up DevToolsUIBindings::DispatchProtocolMessage

content/shell/browser/shell_devtools_frontend.cc

 // Copyright 2013 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/shell/browser/shell_devtools_frontend.h"
 
 #include "base/command_line.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/public/browser/devtools_http_handler.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/content_client.h"
 #include "content/shell/browser/shell.h"
 #include "content/shell/browser/shell_browser_context.h"
 #include "content/shell/browser/shell_browser_main_parts.h"
 #include "content/shell/browser/shell_content_browser_client.h"
 #include "content/shell/browser/shell_devtools_manager_delegate.h"
 #include "content/shell/browser/webkit_test_controller.h"
 #include "content/shell/common/shell_switches.h"
 #include "net/base/filename_util.h"
 
 namespace content {
 
+// This constant should be in sync with
+// the constant at devtools_ui_bindings.cc.
+const size_t kMaxMessageChunkSize = IPC::Channel::kMaximumMessageSize / 4;
+
 // static
 ShellDevToolsFrontend* ShellDevToolsFrontend::Show(
     WebContents* inspected_contents) {
   scoped_refptr<DevToolsAgentHost> agent(
       DevToolsAgentHost::GetOrCreateFor(inspected_contents));
   Shell* shell = Shell::CreateNewWindow(inspected_contents->GetBrowserContext(),
                                         GURL(),
                                         NULL,
                                         MSG_ROUTING_NONE,
                                         gfx::Size());
@@ skipping 83 matching lines @@
   }
 }
 
 void ShellDevToolsFrontend::HandleMessageFromDevToolsFrontendToBackend(
     const std::string& message) {
   agent_host_->DispatchProtocolMessage(message);
 }
 
 void ShellDevToolsFrontend::DispatchProtocolMessage(
     DevToolsAgentHost* agent_host, const std::string& message) {
-  base::StringValue message_value(message);
-  std::string param;
-  base::JSONWriter::Write(&message_value, &param);
-  std::string code = "DevToolsAPI.dispatchMessage(" + param + ");";
-  base::string16 javascript = base::UTF8ToUTF16(code);
-  web_contents()->GetMainFrame()->ExecuteJavaScript(javascript);
+
+  if (message.length() < kMaxMessageChunkSize) {
+    base::string16 javascript = base::UTF8ToUTF16(
+        "DevToolsAPI.dispatchMessage(" + message + ");");
+    web_contents()->GetMainFrame()->ExecuteJavaScript(javascript);
+    return;
+  }
+
+  base::FundamentalValue total_size(static_cast<int>(message.length()));
+  for (size_t pos = 0; pos < message.length(); pos += kMaxMessageChunkSize) {
+    base::StringValue message_value(message.substr(pos, kMaxMessageChunkSize));
+    std::string param;
+    base::JSONWriter::Write(&message_value, &param);
+    std::string code = "DevToolsAPI.dispatchMessageChunk(" + param + ");";
+    base::string16 javascript = base::UTF8ToUTF16(code);
+    web_contents()->GetMainFrame()->ExecuteJavaScript(javascript);
+  }
 }
 
 void ShellDevToolsFrontend::AgentHostClosed(
     DevToolsAgentHost* agent_host, bool replaced) {
   frontend_shell_->Close();
 }
 
 }  // namespace content