Reland "Delete HeadlessBrowserContext::Observer::OnChildContentsCreated."

This is a reland of 888c9108

Original change's description:
> Delete HeadlessBrowserContext::Observer::OnChildContentsCreated.
> 
> This isn't used.
> 
> Change-Id: Id61efee5ce35617c6ab65c6c19a059b36323176f
> Reviewed-on: https://chromium-review.googlesource.com/1065076
> Reviewed-by: Alex Clarke <alexclarke@chromium.org>
> Commit-Queue: Johannes Henkel <johannes@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#559821}

Change-Id: I52e6f2361da7dd900eef24dea4aefd57fa8dda9a
Reviewed-on: https://chromium-review.googlesource.com/1073619Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Commit-Queue: Johannes Henkel <johannes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563046}

headless/lib/browser/headless_browser_context_impl.cc

@@ -384,14 +384,6 @@ void HeadlessBrowserContextImpl::RemoveObserver(Observer* obs) {
   observers_.RemoveObserver(obs);
 }
 
-void HeadlessBrowserContextImpl::NotifyChildContentsCreated(
-    HeadlessWebContentsImpl* parent,
-    HeadlessWebContentsImpl* child) {
-  base::AutoLock lock(observers_lock_);
-  for (auto& observer : observers_)
-    observer.OnChildContentsCreated(parent, child);
-}
-
 void HeadlessBrowserContextImpl::NotifyUrlRequestFailed(
     net::URLRequest* request,
     int net_error,

headless/lib/browser/headless_browser_context_impl.h

@@ -112,9 +112,6 @@ class HEADLESS_EXPORT HeadlessBrowserContextImpl final
   void SetRemoveHeaders(bool should_remove_headers);
   bool ShouldRemoveHeaders() const;
 
-  void NotifyChildContentsCreated(HeadlessWebContentsImpl* parent,
-                                  HeadlessWebContentsImpl* child);
-
   // This will be called on the IO thread.
   void NotifyUrlRequestFailed(net::URLRequest* request,
                               int net_error,

headless/lib/browser/headless_web_contents_impl.cc

@@ -112,8 +112,6 @@ class HeadlessWebContentsImpl::Delegate : public content::WebContentsDelegate {
     HeadlessWebContentsImpl* raw_child_contents = child_contents.get();
     headless_web_contents_->browser_context()->RegisterWebContents(
         std::move(child_contents));
-    headless_web_contents_->browser_context()->NotifyChildContentsCreated(
-        headless_web_contents_, raw_child_contents);
 
     const gfx::Rect default_rect(
         headless_web_contents_->browser()->options()->window_size);
@@ -140,8 +138,6 @@ class HeadlessWebContentsImpl::Delegate : public content::WebContentsDelegate {
                 ->CreateWebContentsBuilder()
                 .SetWindowSize(source->GetContainerBounds().size())
                 .Build());
-        headless_web_contents_->browser_context()->NotifyChildContentsCreated(
-            headless_web_contents_, child_contents);
         target = child_contents->web_contents();
         break;
       }

headless/lib/headless_web_contents_browsertest.cc

@@ -9,6 +9,7 @@
 #include "base/base64.h"
 #include "base/command_line.h"
 #include "base/json/json_writer.h"
+#include "base/logging.h"
 #include "base/run_loop.h"
 #include "base/strings/stringprintf.h"
 #include "base/test/scoped_feature_list.h"
@@ -57,25 +58,6 @@ using testing::UnorderedElementsAre;
 using testing::UnorderedElementsAreArray;
 
 namespace headless {
-
-#define EXPECT_CHILD_CONTENTS_CREATED(obs)                                    \
-  EXPECT_CALL((obs), OnChildContentsCreated(::testing::_, ::testing::_))      \
-      .WillOnce(::testing::DoAll(::testing::SaveArg<0>(&((obs).last_parent)), \
-                                 ::testing::SaveArg<1>(&((obs).last_child))))
-
-class MockHeadlessBrowserContextObserver
-    : public HeadlessBrowserContext::Observer {
- public:
-  MOCK_METHOD2(OnChildContentsCreated,
-               void(HeadlessWebContents*, HeadlessWebContents*));
-
-  MockHeadlessBrowserContextObserver() = default;
-  ~MockHeadlessBrowserContextObserver() override = default;
-
-  HeadlessWebContents* last_parent;
-  HeadlessWebContents* last_child;
-};
-
 class HeadlessWebContentsTest : public HeadlessBrowserTest {};
 
 IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest, Navigation) {
@@ -100,10 +82,6 @@ IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest, WindowOpen) {
   HeadlessBrowserContext* browser_context =
       browser()->CreateBrowserContextBuilder().Build();
 
-  MockHeadlessBrowserContextObserver observer;
-  browser_context->AddObserver(&observer);
-  EXPECT_CHILD_CONTENTS_CREATED(observer);
-
   HeadlessWebContents* web_contents =
       browser_context->CreateWebContentsBuilder()
           .SetInitialURL(embedded_test_server()->GetURL("/window_open.html"))
@@ -112,8 +90,16 @@ IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest, WindowOpen) {
 
   EXPECT_EQ(2u, browser_context->GetAllWebContents().size());
 
-  auto* parent = HeadlessWebContentsImpl::From(observer.last_parent);
-  auto* child = HeadlessWebContentsImpl::From(observer.last_child);
+  HeadlessWebContentsImpl* child = nullptr;
+  HeadlessWebContentsImpl* parent = nullptr;
+  for (HeadlessWebContents* c : browser_context->GetAllWebContents()) {
+    HeadlessWebContentsImpl* impl = HeadlessWebContentsImpl::From(c);
+    if (impl->window_id() == 1)
+      parent = impl;
+    else if (impl->window_id() == 2)
+      child = impl;
+  }
+
   EXPECT_NE(nullptr, parent);
   EXPECT_NE(nullptr, child);
   EXPECT_NE(parent, child);
@@ -131,8 +117,6 @@ IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest, WindowOpen) {
   EXPECT_EQ(expected_bounds.size(),
             child->web_contents()->GetContainerBounds().size());
 #endif  // !defined(OS_MACOSX)
-
-  browser_context->RemoveObserver(&observer);
 }
 
 IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest,
@@ -440,10 +424,6 @@ IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest, BrowserOpenInTab) {
   HeadlessBrowserContext* browser_context =
       browser()->CreateBrowserContextBuilder().Build();
 
-  MockHeadlessBrowserContextObserver observer;
-  browser_context->AddObserver(&observer);
-  EXPECT_CHILD_CONTENTS_CREATED(observer);
-
   HeadlessWebContents* web_contents =
       browser_context->CreateWebContentsBuilder()
           .SetInitialURL(embedded_test_server()->GetURL("/link.html"))
@@ -460,7 +440,6 @@ IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest, BrowserOpenInTab) {
 
   // Check that we have a new tab.
   EXPECT_EQ(2u, browser_context->GetAllWebContents().size());
-  browser_context->RemoveObserver(&observer);
 }
 
 namespace {

headless/public/headless_browser_context.h

@@ -88,9 +88,6 @@ class HEADLESS_EXPORT HeadlessBrowserContext {
 
 class HEADLESS_EXPORT HeadlessBrowserContext::Observer {
  public:
-  // This will be delivered on the UI thread.
-  virtual void OnChildContentsCreated(HeadlessWebContents* parent,
-                                      HeadlessWebContents* child) {}
 
   // Indicates that a network request failed or was canceled. This will be
   // delivered on the IO thread.