[DevTools] Fix frontend host race and assert.

When quickly reloading DevTools, on-load messages from frontend
like Console.enable are dispatched from both page loads, but only the
last batch (from the last reload) should be dispatched. Otherwise,
backend sees messages with the same id, and frontend receives multiple
responses, some of them even before load producing
"dispatchMessage is undefined" error.

Also, reloading frontend violates an assert in DevToolsHost.cpp because of
no proper cleanup in WebDevToolsFrontendImpl.

Drive-by: cleaning up WebDevToolsFrontend and DevToolsHost API.

BUG=566929

Review URL: https://codereview.chromium.org/1504763004

Cr-Commit-Position: refs/heads/master@{#363726}

1 files changed, 1 insertions, 1 deletions

diff --git a/content/renderer/devtools/devtools_client.h b/content/renderer/devtools/devtools_client.h
index a751a31..0dba7f1 100644
--- a/content/renderer/devtools/devtools_client.h
+++ b/content/renderer/devtools/devtools_client.h
@@ -45,8 +45,8 @@ class CONTENT_EXPORT DevToolsClient
   void OnDispatchOnInspectorFrontend(const std::string& message,
                                      uint32 total_size);
 
-  scoped_ptr<blink::WebDevToolsFrontend> web_tools_frontend_;
   std::string compatibility_script_;
+  scoped_ptr<blink::WebDevToolsFrontend> web_tools_frontend_;
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsClient);
 };