Enable control over frame time in SimTests

third_party/WebKit/Source/web/tests/sim/SimCompositor.h

Index: third_party/WebKit/Source/web/tests/sim/SimCompositor.h
diff --git a/third_party/WebKit/Source/web/tests/sim/SimCompositor.h b/third_party/WebKit/Source/web/tests/sim/SimCompositor.h
index 914fab152f30a91a53a67e8b88ec1ae83529e63d..6a3a5cdc813156409b20da0c15ad4a5262848d09 100644
--- a/third_party/WebKit/Source/web/tests/sim/SimCompositor.h
+++ b/third_party/WebKit/Source/web/tests/sim/SimCompositor.h
@@ -30,7 +30,9 @@ class SimCompositor final : public WebLayerTreeView {
 
   // Execute the BeginMainFrame processing steps, an approximation of what
   // cc::ThreadProxy::BeginMainFrame would do.
+  // If time is not specified a 60Hz frame rate time progression is used.
   SimDisplayItemList beginFrame();
+  SimDisplayItemList beginFrame(double timeInSeconds);

[esprehn, 2017/03/14 05:54:12]

If we make this:

(double timeInSeconds = 0.016)

with a default argument, and then make the code be += inside the function and
callers just keep passing the time to advance to that feels like better
ergonomics to me, maybe I don't understand how you plan to use this in your
testing patch though? Do you have an example?

 
   bool needsBeginFrame() const { return m_needsBeginFrame; }
   bool deferCommits() const { return m_deferCommits; }