Ensure that the web contents trying to access native VR Shell is the webcontents we created.

BUG=641413

Review-Url: https://codereview.chromium.org/2384323003
Cr-Commit-Position: refs/heads/master@{#422812}

chrome/browser/android/vr_shell/vr_shell.cc

@@ -657,9 +657,12 @@ void VrShell::OnResume(JNIEnv* env, const JavaParamRef<jobject>& obj) {
   controller_->OnResume();
 }
 
-base::WeakPtr<VrShell> VrShell::GetWeakPtr() {
-  // TODO: Ensure that only ui webcontents can request this weak ptr.
-  if (g_instance != nullptr)
+base::WeakPtr<VrShell> VrShell::GetWeakPtr(
+    const content::WebContents* web_contents) {
+  // Ensure that the WebContents requesting the VrShell instance is the one
+  // we created.
+  if (g_instance != nullptr &&
+      g_instance->ui_cvc_->GetWebContents() == web_contents)
     return g_instance->weak_ptr_factory_.GetWeakPtr();
   return base::WeakPtr<VrShell>(nullptr);
 }

chrome/browser/android/vr_shell/vr_shell.h

@@ -21,6 +21,7 @@
 
 namespace content {
 class ContentViewCore;
+class WebContents;
 }
 
 namespace ui {
@@ -66,7 +67,8 @@ class VrShell : public device::GvrDelegate {
                     bool enabled);
 
   // html/js UI hooks.
-  static base::WeakPtr<VrShell> GetWeakPtr();
+  static base::WeakPtr<VrShell> GetWeakPtr(
+      const content::WebContents* web_contents);
   UiScene* GetScene();
   void OnDomContentsLoaded();
   void SetUiTextureSize(int width, int height);

chrome/browser/ui/webui/vr_shell/vr_shell_ui_message_handler.cc

@@ -18,7 +18,7 @@ VrShellUIMessageHandler::VrShellUIMessageHandler() {}
 VrShellUIMessageHandler::~VrShellUIMessageHandler() {}
 
 void VrShellUIMessageHandler::RegisterMessages() {
-  vr_shell_ = vr_shell::VrShell::GetWeakPtr();
+  vr_shell_ = vr_shell::VrShell::GetWeakPtr(web_ui()->GetWebContents());
 
   web_ui()->RegisterMessageCallback(
       "domLoaded", base::Bind(&VrShellUIMessageHandler::HandleDomLoaded,