cc: Allow sending BeginMainFrame before draw or activation

cc/base/switches.cc

 // Copyright (c) 2012 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.
 
 #include "cc/base/switches.h"
 
 #include "base/command_line.h"
 
 namespace cc {
 namespace switches {
@@ skipping 19 matching lines @@
 // Disables the deadline scheduler.
 // Overrides the kDisableDeadlineScheduling flag.
 const char kDisableDeadlineScheduling[] = "disable-deadline-scheduling";
 
 // Deadline scheduling gives children compositors and the main thread an
 // interval over which they can produce content instead of always consuming
 // their input on the next BeginFrame. This allows a total pipeline latency
 // of less than 1 vsync if their intervals are properly nested.
 const char kEnableDeadlineScheduling[] = "enable-deadline-scheduling";
 
+// Disables the starting the next commit before the previous commit has drawn.
+// Overrides the kEnableStartCommitBeforeDraw flag.
+const char kDisableStartCommitBeforeDraw[] = "disable-start-commit-before-draw";
+
+// Allows the next commit to start before the previous commit has drawn.
+const char kEnableStartCommitBeforeDraw[] = "enable-start-commit-before-draw";
+
+// Disables the starting the next commit before the previous commit activates.
+// Overrides the kEnableStartCommitBeforeDraw flag.
+const char kDisableStartCommitBeforeActivate[] =
+    "disable-start-commit-before-activate";
+
+// Allows the next commit to start before the previous commit activates.
+const char kEnableStartCommitBeforeActivate[] =
+    "enable-start-commit-before-activate";
+
 const char kEnableTopControlsPositionCalculation[] =
     "enable-top-controls-position-calculation";
 
 // For any layers that can get drawn directly to screen, draw them with the Skia
 // GPU backend.  Only valid with gl rendering + threaded compositing + impl-side
 // painting.
 const char kForceDirectLayerDrawing[] = "force-direct-layer-drawing";
 
 // The height of the movable top controls.
 const char kTopControlsHeight[] = "top-controls-height";
@@ skipping 129 matching lines @@
   else if (command_line.HasSwitch(cc::switches::kEnableDeadlineScheduling))
     return true;
 
 #if defined(OS_ANDROID)
   return true;
 #else
   return false;
 #endif
 }
 
+bool IsStartCommitBeforeDrawEnabled() {
+  // Starting the commit before activation implies starting the commit
+  // before draw as well.
+  if (IsStartCommitBeforeActivateEnabled())
+    return true;
+
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(cc::switches::kDisableStartCommitBeforeDraw))
+    return false;
+  else if (command_line.HasSwitch(cc::switches::kEnableStartCommitBeforeDraw))
+    return true;
+
+#if defined(OS_ANDROID)
+  return true;
+#else
+  return false;
+#endif
+}
+
+bool IsStartCommitBeforeActivateEnabled() {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(cc::switches::kDisableStartCommitBeforeActivate))
+    return false;
+  else if (
+      command_line.HasSwitch(cc::switches::kEnableStartCommitBeforeActivate))
+    return true;
+
+#if defined(OS_ANDROID)
+  return true;
+#else
+  return false;
+#endif
+}
+
 }  // namespace switches
 }  // namespace cc