cc: Allow sending BeginMainFrame before draw or activation

cc/base/switches.h

Index: cc/base/switches.h
diff --git a/cc/base/switches.h b/cc/base/switches.h
index c418ade5cfe6ee41488c70a993b88f44df7cb9a4..922bf4d44a6ebcc27b22b3abea4eed6aa89334fd 100644
--- a/cc/base/switches.h
+++ b/cc/base/switches.h
@@ -21,6 +21,10 @@ CC_EXPORT extern const char kDisableImplSidePainting[];
 CC_EXPORT extern const char kDisableThreadedAnimation[];
 CC_EXPORT extern const char kDisableCompositedAntialiasing[];
 CC_EXPORT extern const char kEnableImplSidePainting[];
+CC_EXPORT extern const char kDisableStartCommitBeforeDraw[];
+CC_EXPORT extern const char kEnableStartCommitBeforeDraw[];
+CC_EXPORT extern const char kDisableStartCommitBeforeActivate[];
+CC_EXPORT extern const char kEnableStartCommitBeforeActivate[];
 CC_EXPORT extern const char kEnableTopControlsPositionCalculation[];
 CC_EXPORT extern const char kForceDirectLayerDrawing[];
 CC_EXPORT extern const char kJankInsteadOfCheckerboard[];
@@ -69,6 +73,8 @@ CC_EXPORT extern const char kUIShowNonOccludingRects[];
 CC_EXPORT extern const char kCCLayerTreeTestNoTimeout[];
 
 CC_EXPORT bool IsDeadlineSchedulingEnabled();
+CC_EXPORT bool IsStartCommitBeforeDrawEnabled();
+CC_EXPORT bool IsStartCommitBeforeActivateEnabled();
 CC_EXPORT bool IsImplSidePaintingEnabled();
 CC_EXPORT bool IsMapImageEnabled();