Makes mojo WebUI run main only after page finishes loading

This way there isn't possible race conditions if main is run before
the page finishes loading.

BUG=none
TEST=none
R=darin@chromium.org

Review URL: https://codereview.chromium.org/215373004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@260266 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/render_process_host_impl.cc

@@ -2157,8 +2157,8 @@ void RenderProcessHostImpl::DecrementWorkerRefCount() {
 
 #if defined(USE_MOJO)
 void RenderProcessHostImpl::SetWebUIHandle(
-int32 view_routing_id,
-mojo::ScopedMessagePipeHandle handle) {
+    int32 view_routing_id,
+    mojo::ScopedMessagePipeHandle handle) {
   if (!render_process_host_mojo_)
     render_process_host_mojo_.reset(new RenderProcessHostMojoImpl(this));
   render_process_host_mojo_->SetWebUIHandle(view_routing_id, handle.Pass());

content/browser/renderer_host/render_process_host_mojo_impl.h

@@ -15,7 +15,6 @@ namespace content {
 class MojoChannelInit;
 class RenderProcessHost;
 
-
 // RenderProcessHostMojoImpl is responsible for initiating and maintaining the
 // connection with the content side of RenderProcessHostMojo.
 class RenderProcessHostMojoImpl : public RenderProcessHostMojo {

content/renderer/web_ui_mojo.cc

@@ -41,18 +41,23 @@ void WebUIMojo::MainFrameObserver::WillReleaseScriptContext(
   web_ui_mojo_->DestroyContextState(context);
 }
 
+void WebUIMojo::MainFrameObserver::DidFinishDocumentLoad() {
+  web_ui_mojo_->OnDidFinishDocumentLoad();
+}
+
 WebUIMojo::WebUIMojo(RenderView* render_view)
     : RenderViewObserver(render_view),
       RenderViewObserverTracker<WebUIMojo>(render_view),
-      main_frame_observer_(this) {
+      main_frame_observer_(this),
+      did_finish_document_load_(false) {
   CreateContextState();
 }
 
 void WebUIMojo::SetBrowserHandle(mojo::ScopedMessagePipeHandle handle) {
-  v8::HandleScope handle_scope(blink::mainThreadIsolate());
-  WebUIMojoContextState* state = GetContextState();
-  if (state)
-    state->SetHandle(handle.Pass());
+  if (did_finish_document_load_)
+    SetHandleOnContextState(handle.Pass());
+  else
+    pending_handle_ = handle.Pass();
 }
 
 WebUIMojo::~WebUIMojo() {
@@ -76,6 +81,20 @@ void WebUIMojo::DestroyContextState(v8::Handle<v8::Context> context) {
   context_data->RemoveUserData(kWebUIMojoContextStateKey);
 }
 
+void WebUIMojo::OnDidFinishDocumentLoad() {
+  did_finish_document_load_ = true;
+  if (pending_handle_.is_valid())
+    SetHandleOnContextState(pending_handle_.Pass());
+}
+
+void WebUIMojo::SetHandleOnContextState(mojo::ScopedMessagePipeHandle handle) {
+  DCHECK(did_finish_document_load_);
+  v8::HandleScope handle_scope(blink::mainThreadIsolate());
+  WebUIMojoContextState* state = GetContextState();
+  if (state)
+    state->SetHandle(handle.Pass());
+}
+
 WebUIMojoContextState* WebUIMojo::GetContextState() {
   blink::WebFrame* frame = render_view()->GetWebView()->mainFrame();
   v8::HandleScope handle_scope(blink::mainThreadIsolate());

content/renderer/web_ui_mojo.h

@@ -42,6 +42,7 @@ class WebUIMojo
     // RenderFrameObserver overrides:
     virtual void WillReleaseScriptContext(v8::Handle<v8::Context> context,
                                           int world_id) OVERRIDE;
+    virtual void DidFinishDocumentLoad() OVERRIDE;
 
    private:
     WebUIMojo* web_ui_mojo_;
@@ -54,6 +55,13 @@ class WebUIMojo
   void CreateContextState();
   void DestroyContextState(v8::Handle<v8::Context> context);
 
+  // Invoked when the frame finishes loading. Invokes SetHandleOnContextState()
+  // if necessary.
+  void OnDidFinishDocumentLoad();
+
+  // Invokes SetHandle() on the WebUIMojoContextState (if there is one).
+  void SetHandleOnContextState(mojo::ScopedMessagePipeHandle handle);
+
   WebUIMojoContextState* GetContextState();
 
   // RenderViewObserver overrides:
@@ -62,6 +70,16 @@ class WebUIMojo
 
   MainFrameObserver main_frame_observer_;
 
+  // Set to true in DidFinishDocumentLoad(). 'main' is only executed once this
+  // happens.
+  bool did_finish_document_load_;
+
+  // If SetBrowserHandle() is invoked before the document finishes loading the
+  // MessagePipeHandle is stored here. When the document finishes loading
+  // SetHandleOnContextState() is invoked to send the handle to the
+  // WebUIMojoContextState and ultimately the page.
+  mojo::ScopedMessagePipeHandle pending_handle_;
+
   DISALLOW_COPY_AND_ASSIGN(WebUIMojo);
 };
 

content/renderer/web_ui_mojo_context_state.cc

@@ -113,7 +113,7 @@ void WebUIMojoContextState::OnFetchModuleComplete(
   DCHECK_EQ(kModulePrefix,
       response.url().string().utf8().substr(0, arraysize(kModulePrefix) - 1));
   const std::string module =
-      response.url().string().utf8().substr(arraysize(kModulePrefix));
+      response.url().string().utf8().substr(arraysize(kModulePrefix) - 1);
   // We can't delete fetch right now as the arguments to this function come from
   // it and are used below. Instead use a scope_ptr to cleanup.
   scoped_ptr<ResourceFetcher> deleter(fetcher);