blimp: Hook up the layer holding the tab content into Chrome.

chrome/browser/android/tab_android.cc

 // Copyright 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 "chrome/browser/android/tab_android.h"
 
 #include <stddef.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
@@ skipping 398 matching lines @@
 
   // Verify that the WebContents this tab represents matches the expected
   // off the record state.
   CHECK_EQ(GetProfile()->IsOffTheRecord(), incognito);
 
   InstantService* instant_service =
       InstantServiceFactory::GetForProfile(GetProfile());
   if (instant_service)
     instant_service->AddObserver(this);
 
-  content_layer_->InsertChild(web_contents_->GetNativeView()->GetLayer(), 0);
+  if (!blimp_contents_)
+    content_layer_->InsertChild(web_contents_->GetNativeView()->GetLayer(), 0);
 }
 
 base::android::ScopedJavaLocalRef<jobject> TabAndroid::InitBlimpContents(
     JNIEnv* env,
     const JavaParamRef<jobject>& obj,
     const JavaParamRef<jobject>& j_profile) {
   Profile* profile = ProfileAndroid::FromProfileAndroid(j_profile.obj());
   DCHECK(!profile->IsOffTheRecord());
   blimp::client::BlimpClientContext* context =
       BlimpClientContextFactory::GetForBrowserContext(profile);
   DCHECK(context);
   blimp_contents_ = context->CreateBlimpContents();
   DCHECK(blimp_contents_);
+
+  // Let's detach the layer from WebContents first, just to be sure.
+  cc::Layer* web_contents_layer = web_contents_->GetNativeView()->GetLayer();

[nyquist, 2016/08/29 23:09:45]

Are you sure web_contents_ is never nullptr here?

[Khushal, 2016/08/30 00:51:10]

Thanks for catching it. Done.

+  if (web_contents_layer->parent() == content_layer_.get())
+    web_contents_layer->RemoveFromParent();
+
+  // Attach the layer holding the tab contents to the |content_layer_|.
+  content_layer_->InsertChild(blimp_contents_->GetNativeView()->GetLayer(), 0);
+
   return blimp_contents_->GetJavaObject();
 }
 
 void TabAndroid::UpdateDelegates(
     JNIEnv* env,
     const JavaParamRef<jobject>& obj,
     const JavaParamRef<jobject>& jweb_contents_delegate,
     const JavaParamRef<jobject>& jcontext_menu_populator) {
   ContextMenuHelper::FromWebContents(web_contents())->SetPopulator(
       jcontext_menu_populator);
@@ skipping 455 matching lines @@
 static void Init(JNIEnv* env, const JavaParamRef<jobject>& obj) {
   TRACE_EVENT0("native", "TabAndroid::Init");
   // This will automatically bind to the Java object and pass ownership there.
   new TabAndroid(env, obj);
 }
 
 // static
 bool TabAndroid::RegisterTabAndroid(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }