cc: Making BeginFrameSources support multiple BeginFrameObservers.

cc/test/scheduler_test_common.h

 // Copyright 2011 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.
 
 #ifndef CC_TEST_SCHEDULER_TEST_COMMON_H_
 #define CC_TEST_SCHEDULER_TEST_COMMON_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 58 matching lines @@
   ~TestDelayBasedTimeSource() override;
   base::TimeTicks Now() const override;
   std::string TypeString() const override;
 
   scoped_refptr<TestNowSource> now_src_;
 };
 
 struct FakeBeginFrameSource : public BeginFrameSourceMixIn {
   bool remaining_frames_ = false;
 
-  BeginFrameObserver* GetObserver() { return observer_; }
+  BeginFrameObserver* GetObserver() {
+    if ((observer_list_).might_have_observers()) {
+      ObserverList<BeginFrameObserver>::Iterator it(&observer_list_);
+      BeginFrameObserver* obs;
+      while ((obs = it.GetNext()) != nullptr) {
+        return obs;
+      }
+    }
+    return nullptr;
+  }
 
   BeginFrameArgs TestLastUsedBeginFrameArgs() {
-    if (observer_) {
-      return observer_->LastUsedBeginFrameArgs();
+    BeginFrameObserver* obs = GetObserver();
+    if (obs) {
+      return obs->LastUsedBeginFrameArgs();
     }
     return BeginFrameArgs();
   }
   void TestOnBeginFrame(const BeginFrameArgs& args) {
     return CallOnBeginFrame(args);
   }
 
   // BeginFrameSource
   void DidFinishFrame(size_t remaining_frames) override;
-  void AsValueInto(base::trace_event::TracedValue* dict) const override;
+  void AsValueInto(base::trace_event::TracedValue* dict) override;
 
   ~FakeBeginFrameSource() override {}
 };
 
 class TestBackToBackBeginFrameSource : public BackToBackBeginFrameSource {
  public:
   ~TestBackToBackBeginFrameSource() override;
 
   static scoped_ptr<TestBackToBackBeginFrameSource> Create(
       scoped_refptr<TestNowSource> now_src,
@@ skipping 105 matching lines @@
       const scoped_refptr<OrderedSimpleTaskRunner>& test_task_runner,
       TestSchedulerFrameSourcesConstructor* frame_sources_constructor,
       scoped_ptr<BeginFrameSource> external_begin_frame_source);
 
   scoped_refptr<TestNowSource> now_src_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_SCHEDULER_TEST_COMMON_H_