Remove "mixin" from BeginFrameSource/Observer base classes.

cc/scheduler/begin_frame_source_unittest.cc

Index: cc/scheduler/begin_frame_source_unittest.cc
diff --git a/cc/scheduler/begin_frame_source_unittest.cc b/cc/scheduler/begin_frame_source_unittest.cc
index 22126bead4504af443d585740c491a68710833a9..71f42dea5c9bfb41d69c48dc4ffb46c9e67fe189 100644
--- a/cc/scheduler/begin_frame_source_unittest.cc
+++ b/cc/scheduler/begin_frame_source_unittest.cc
@@ -170,16 +170,16 @@ const BeginFrameArgs MockBeginFrameObserver::kDefaultBeginFrameArgs =
         -1,
         -1);
 
-// BeginFrameObserverMixIn testing ---------------------------------------
-class MockMinimalBeginFrameObserverMixIn : public BeginFrameObserverMixIn {
+// BeginFrameObserverBase testing ---------------------------------------
+class MockMinimalBeginFrameObserverBase : public BeginFrameObserverBase {
  public:
   MOCK_METHOD1(OnBeginFrameMixInDelegate, bool(const BeginFrameArgs&));
   int64_t dropped_begin_frame_args() const { return dropped_begin_frame_args_; }
 };
 
-TEST(BeginFrameObserverMixInTest, OnBeginFrameImplementation) {
+TEST(BeginFrameObserverBaseTest, OnBeginFrameImplementation) {
   using ::testing::Return;
-  MockMinimalBeginFrameObserverMixIn obs;
+  MockMinimalBeginFrameObserverBase obs;
   ::testing::InSequence ordered;  // These calls should be ordered
 
   // Initial conditions
@@ -280,7 +280,7 @@ TEST(BeginFrameSourceMixInTest, NeedsBeginFrames) {
   EXPECT_FALSE(source.NeedsBeginFrames());
 }
 
-class LoopingBeginFrameObserver : public BeginFrameObserverMixIn {
+class LoopingBeginFrameObserver : public BeginFrameObserverBase {
  public:
   BeginFrameSource* source_;
 
@@ -292,7 +292,7 @@ class LoopingBeginFrameObserver : public BeginFrameObserverMixIn {
   }
 
  protected:
-  // BeginFrameObserverMixIn
+  // BeginFrameObserverBase
   bool OnBeginFrameMixInDelegate(const BeginFrameArgs& args) override {

[sunnyps, 2015/05/26 21:45:44]

Please rename OnBeginFrameMixInDelegate too. I would suggest
OnBeginFrameDerivedImpl or something like that.

     return true;
   }