Convert the enum objects in cc/scheduler/scheduler_state_machine.h to C++ "enum class" objects

cc/scheduler/scheduler_state_machine.h

Index: cc/scheduler/scheduler_state_machine.h
diff --git a/cc/scheduler/scheduler_state_machine.h b/cc/scheduler/scheduler_state_machine.h
index 7509819c1d7f114d265a1c230d24b78507edbbb0..3bf721d7be8f44e47a8fee6d890459871e247159 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -42,58 +42,73 @@ class CC_EXPORT SchedulerStateMachine {
   // settings must be valid for the lifetime of this class.
   explicit SchedulerStateMachine(const SchedulerSettings& settings);
 
-  enum OutputSurfaceState {
-    OUTPUT_SURFACE_ACTIVE,
-    OUTPUT_SURFACE_LOST,
-    OUTPUT_SURFACE_CREATING,
-    OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT,
-    OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION,
+  enum class OutputSurfaceState {
+    ACTIVE,
+    LOST,
+    CREATING,
+    WAITING_FOR_FIRST_COMMIT,
+    WAITING_FOR_FIRST_ACTIVATION,
   };
   static const char* OutputSurfaceStateToString(OutputSurfaceState state);
 
+  friend ::std::ostream& operator<<(::std::ostream& os,

[Sami, 2015/01/07 14:13:03]

It's unfortunate that we need to add these just for gtest. I wonder if there's a
gtest bug with enum classes that should be fixed instead?

[jamesr, 2015/01/07 22:32:00]

enum classes, unlike enums, aren't implicitly convertible to integers so if
gtest wants to print it out it has to be taught a way to do so.

instead of having this friend stuff, imo it's better to declare a PrintTo(const
T&, std::ostream*) function in the same namespace as T so ADL can find it. with
this model you can out-of-line the stream manipulations instead of putting the
super bloaty ostream template instantiations in the header file

[Shanmuga Pandi, 2015/01/08 05:13:30]

I think PrintTo will solve gtest print issue.
But DCHECK_EQ() also need operator << oveloads.
If I not overload <<, then DCHECK_EQ gives compilation error.

+                                    const OutputSurfaceState& state) {
+    return os << OutputSurfaceStateToString(state);
+  }
+
   // Note: BeginImplFrameState will always cycle through all the states in
   // order. Whether or not it actually waits or draws, it will at least try to
-  // wait in BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME and try to draw in
-  // BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE
-  enum BeginImplFrameState {
-    BEGIN_IMPL_FRAME_STATE_IDLE,
-    BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING,
-    BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME,
-    BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE,
+  // wait in INSIDE_BEGIN_FRAME and try to draw in
+  // INSIDE_DEADLINE
+  enum class BeginImplFrameState {
+    IDLE,
+    BEGIN_FRAME_STARTING,
+    INSIDE_BEGIN_FRAME,
+    INSIDE_DEADLINE,
   };
   static const char* BeginImplFrameStateToString(BeginImplFrameState state);
 
-  enum BeginImplFrameDeadlineMode {
-    BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE,
-    BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR,
-    BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE,
+  friend ::std::ostream& operator<<(::std::ostream& os,
+                                    const BeginImplFrameState& state) {
+    return os << BeginImplFrameStateToString(state);
+  }
+
+  enum class BeginImplFrameDeadlineMode {
+    IMMEDIATE,
+    REGULAR,
+    LATE,
   };
   static const char* BeginImplFrameDeadlineModeToString(
       BeginImplFrameDeadlineMode mode);
 
-  enum CommitState {
-    COMMIT_STATE_IDLE,
-    COMMIT_STATE_BEGIN_MAIN_FRAME_SENT,
-    COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED,
-    COMMIT_STATE_READY_TO_COMMIT,
-    COMMIT_STATE_WAITING_FOR_ACTIVATION,
-    COMMIT_STATE_WAITING_FOR_DRAW,
+  enum class CommitState {
+    IDLE,
+    BEGIN_MAIN_FRAME_SENT,
+    BEGIN_MAIN_FRAME_STARTED,
+    READY_TO_COMMIT,
+    WAITING_FOR_ACTIVATION,
+    WAITING_FOR_DRAW,
   };
   static const char* CommitStateToString(CommitState state);
 
-  enum ForcedRedrawOnTimeoutState {
-    FORCED_REDRAW_STATE_IDLE,
-    FORCED_REDRAW_STATE_WAITING_FOR_COMMIT,
-    FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION,
-    FORCED_REDRAW_STATE_WAITING_FOR_DRAW,
+  friend ::std::ostream& operator<<(::std::ostream& os,
+                                    const CommitState& state) {
+    return os << CommitStateToString(state);
+  }
+
+  enum class ForcedRedrawOnTimeoutState {
+    IDLE,
+    WAITING_FOR_COMMIT,
+    WAITING_FOR_ACTIVATION,
+    WAITING_FOR_DRAW,
   };
   static const char* ForcedRedrawOnTimeoutStateToString(
       ForcedRedrawOnTimeoutState state);
 
   bool CommitPending() const {
-    return commit_state_ == COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
-           commit_state_ == COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED ||
-           commit_state_ == COMMIT_STATE_READY_TO_COMMIT;
+    return commit_state_ == CommitState::BEGIN_MAIN_FRAME_SENT ||
+           commit_state_ == CommitState::BEGIN_MAIN_FRAME_STARTED ||
+           commit_state_ == CommitState::READY_TO_COMMIT;
   }
   CommitState commit_state() const { return commit_state_; }
 
@@ -101,16 +116,16 @@ class CC_EXPORT SchedulerStateMachine {
   bool PrepareTilesPending() const { return needs_prepare_tiles_; }
 
   enum Action {
-    ACTION_NONE,
-    ACTION_ANIMATE,
-    ACTION_SEND_BEGIN_MAIN_FRAME,
-    ACTION_COMMIT,
-    ACTION_ACTIVATE_SYNC_TREE,
-    ACTION_DRAW_AND_SWAP_IF_POSSIBLE,
-    ACTION_DRAW_AND_SWAP_FORCED,
-    ACTION_DRAW_AND_SWAP_ABORT,
-    ACTION_BEGIN_OUTPUT_SURFACE_CREATION,
-    ACTION_PREPARE_TILES,
+    NONE,
+    ANIMATE,
+    SEND_BEGIN_MAIN_FRAME,
+    COMMIT,
+    ACTIVATE_SYNC_TREE,
+    DRAW_AND_SWAP_IF_POSSIBLE,
+    DRAW_AND_SWAP_FORCED,
+    DRAW_AND_SWAP_ABORT,
+    BEGIN_OUTPUT_SURFACE_CREATION,
+    PREPARE_TILES,
   };
   static const char* ActionToString(Action action);