web-threads: Create a single instance of WebThread for each blink thread.

content/test/test_blink_web_unit_test_support.cc

 // Copyright 2013 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 "content/test/test_blink_web_unit_test_support.h"
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/path_service.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/public/common/content_switches.h"
 #include "content/renderer/scheduler/renderer_scheduler.h"
 #include "content/renderer/scheduler/web_scheduler_impl.h"
+#include "content/renderer/scheduler/webthread_impl_for_scheduler.h"
 #include "content/test/mock_webclipboard_impl.h"
 #include "content/test/web_gesture_curve_mock.h"
 #include "content/test/web_layer_tree_view_impl_for_testing.h"
 #include "content/test/weburl_loader_mock_factory.h"
 #include "media/base/media.h"
 #include "net/cookies/cookie_monster.h"
 #include "net/test/spawned_test_server/spawned_test_server.h"
 #include "storage/browser/database/vfs_backend.h"
 #include "third_party/WebKit/public/platform/WebData.h"
 #include "third_party/WebKit/public/platform/WebFileSystem.h"
@@ skipping 27 matching lines @@
   url_loader_factory_.reset(new WebURLLoaderMockFactory());
   mock_clipboard_.reset(new MockWebClipboardImpl());
 
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
   gin::IsolateHolder::LoadV8Snapshot();
 #endif
 
   if (base::MessageLoopProxy::current()) {
     renderer_scheduler_ = RendererScheduler::Create();
     web_scheduler_.reset(new WebSchedulerImpl(renderer_scheduler_.get()));
+    web_thread_.reset(new WebThreadImplForScheduler(renderer_scheduler_.get()));
   }
 
   blink::initialize(this);
   blink::setLayoutTestMode(true);
   blink::WebSecurityPolicy::registerURLSchemeAsLocal(
       blink::WebString::fromUTF8("test-shell-resource"));
   blink::WebSecurityPolicy::registerURLSchemeAsNoAccess(
       blink::WebString::fromUTF8("test-shell-resource"));
   blink::WebSecurityPolicy::registerURLSchemeAsDisplayIsolated(
       blink::WebString::fromUTF8("test-shell-resource"));
@@ skipping 239 matching lines @@
 bool TestBlinkWebUnitTestSupport::getBlobItems(
     const blink::WebString& uuid,
     blink::WebVector<blink::WebBlobData::Item*>* items) {
   return blob_registry_.GetBlobItems(uuid, items);
 }
 
 blink::WebScheduler* TestBlinkWebUnitTestSupport::scheduler() {
   return web_scheduler_.get();
 }
 
+blink::WebThread* TestBlinkWebUnitTestSupport::currentThread() {

[Sami, 2015/03/02 11:40:02]

I'm wondering if we should just register web_thread_ into the TLS instead of
overriding this method here (and doing the same in RendererBlinkPlatformImpl)?
That would require a little less special casing, but then again TLS lookups can
be slow on some platforms. WDYT?

[sadrul, 2015/03/02 16:53:21]

From our earlier discussion
(https://codereview.chromium.org/959803003/diff/180001/content/child/blink_pla...),
it may be possible to just get rid of the TLS we maintain in BlinkPlatformImpl
since currentThread() is only called on main-thread. In that case, we would need
overrides in both RendererBlinkPlatformImpl and here.

[Sami, 2015/03/02 17:25:06]

Interesting. Maybe that code should be migrated to this:

https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

(Note: I'm in the middle of moving clients of WTF::callOnMain to that too.)

+  if (web_thread_ && web_thread_->isCurrentThread())
+    return web_thread_.get();
+  return BlinkPlatformImpl::currentThread();
+}
+
 }  // namespace content