cc: Redraw incomplete frames when new texture uploads finish

cc/scheduler_state_machine.cc

Index: cc/scheduler_state_machine.cc
diff --git a/cc/scheduler_state_machine.cc b/cc/scheduler_state_machine.cc
index 60a1ce9a3a1dffb0892ebf0fc45e3f64660f43bf..0e3c2630471491bf2cecfae0ffb377d2ebc7a2ce 100644
--- a/cc/scheduler_state_machine.cc
+++ b/cc/scheduler_state_machine.cc
@@ -16,9 +16,11 @@ SchedulerStateMachine::SchedulerStateMachine(const LayerTreeSettings &layerTreeS
     , m_currentFrameNumber(0)
     , m_lastFrameNumberWhereDrawWasCalled(-1)
     , m_lastFrameNumberWhereTreeActivationAttempted(-1)
+    , m_lastFrameNumberWhereRedrawOnVisibleTextureUploadAttempted(-1)
     , m_consecutiveFailedDraws(0)
     , m_maximumNumberOfFailedDrawsBeforeDrawIsForced(3)
     , m_needsRedraw(false)
+    , m_needsRedrawOnVisibleTextureUpload(false)
     , m_needsForcedRedraw(false)
     , m_needsForcedRedrawAfterNextCommit(false)
     , m_needsCommit(false)
@@ -45,6 +47,7 @@ std::string SchedulerStateMachine::toString()
     base::StringAppendF(&str, "m_consecutiveFailedDraws = %d; ", m_consecutiveFailedDraws);
     base::StringAppendF(&str, "m_maximumNumberOfFailedDrawsBeforeDrawIsForced = %d; ", m_maximumNumberOfFailedDrawsBeforeDrawIsForced);
     base::StringAppendF(&str, "m_needsRedraw = %d; ", m_needsRedraw);
+    base::StringAppendF(&str, "m_needsRedrawOnVisibleTextureUpload = %d; ", m_needsRedrawOnVisibleTextureUpload);
     base::StringAppendF(&str, "m_needsForcedRedraw = %d; ", m_needsForcedRedraw);
     base::StringAppendF(&str, "m_needsForcedRedrawAfterNextCommit = %d; ", m_needsForcedRedrawAfterNextCommit);
     base::StringAppendF(&str, "m_needsCommit = %d; ", m_needsCommit);
@@ -72,6 +75,12 @@ bool SchedulerStateMachine::hasAttemptedTreeActivationThisFrame() const
     return m_currentFrameNumber == m_lastFrameNumberWhereTreeActivationAttempted;
 }
 
+bool SchedulerStateMachine::hasAttemptedRedrawOnVisibleTextureUploadThisFrame() const
+{
+    return m_currentFrameNumber ==
+           m_lastFrameNumberWhereRedrawOnVisibleTextureUploadAttempted;
+}
+
 bool SchedulerStateMachine::drawSuspendedUntilCommit() const
 {
     if (!m_canDraw)
@@ -110,7 +119,14 @@ bool SchedulerStateMachine::shouldDraw() const
 
 bool SchedulerStateMachine::shouldAttemptTreeActivation() const
 {
-  return m_hasPendingTree && m_insideVSync && !hasAttemptedTreeActivationThisFrame();
+    return m_hasPendingTree && m_insideVSync && !hasAttemptedTreeActivationThisFrame();
+}
+
+bool SchedulerStateMachine::shouldAttemptRedrawOnVisibleTextureUpload() const
+{
+    return m_needsRedrawOnVisibleTextureUpload &&
+           !hasAttemptedRedrawOnVisibleTextureUploadThisFrame() &&
+           !hasDrawnThisFrame();
 }
 
 bool SchedulerStateMachine::shouldAcquireLayerTexturesForMainThread() const
@@ -149,6 +165,8 @@ SchedulerStateMachine::Action SchedulerStateMachine::nextAction() const
             return ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED;
         if (shouldDraw())
             return m_needsForcedRedraw ? ACTION_DRAW_FORCED : ACTION_DRAW_IF_POSSIBLE;
+        if (shouldAttemptRedrawOnVisibleTextureUpload())
+            return ACTION_CHECK_FOR_NEW_VISIBLE_TEXTURES;
         if (m_needsCommit && ((m_visible && m_canBeginFrame) || m_needsForcedCommit))
             // TODO(enne): Should probably drop the active tree on force commit
             return m_hasPendingTree ? ACTION_NONE : ACTION_BEGIN_FRAME;
@@ -159,6 +177,8 @@ SchedulerStateMachine::Action SchedulerStateMachine::nextAction() const
             return ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED;
         if (shouldDraw())
             return m_needsForcedRedraw ? ACTION_DRAW_FORCED : ACTION_DRAW_IF_POSSIBLE;
+        if (shouldAttemptRedrawOnVisibleTextureUpload())
+            return ACTION_CHECK_FOR_NEW_VISIBLE_TEXTURES;
         return ACTION_NONE;
 
     case COMMIT_STATE_READY_TO_COMMIT:
@@ -169,6 +189,8 @@ SchedulerStateMachine::Action SchedulerStateMachine::nextAction() const
             return ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED;
         if (shouldDraw() || m_outputSurfaceState == OUTPUT_SURFACE_LOST)
             return m_needsForcedRedraw ? ACTION_DRAW_FORCED : ACTION_DRAW_IF_POSSIBLE;
+        if (shouldAttemptRedrawOnVisibleTextureUpload())
+            return ACTION_CHECK_FOR_NEW_VISIBLE_TEXTURES;
         // COMMIT_STATE_WAITING_FOR_FIRST_DRAW wants to enforce a draw. If m_canDraw is false
         // or textures are not available, proceed to the next step (similar as in COMMIT_STATE_IDLE).
         bool canCommit = m_visible || m_needsForcedCommit;
@@ -182,6 +204,8 @@ SchedulerStateMachine::Action SchedulerStateMachine::nextAction() const
             return ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED;
         if (m_needsForcedRedraw)
             return ACTION_DRAW_FORCED;
+        if (shouldAttemptRedrawOnVisibleTextureUpload())
+            return ACTION_CHECK_FOR_NEW_VISIBLE_TEXTURES;
         return ACTION_NONE;
     }
     NOTREACHED();
@@ -198,6 +222,13 @@ void SchedulerStateMachine::updateState(Action action)
         m_lastFrameNumberWhereTreeActivationAttempted = m_currentFrameNumber;
         return;
 
+    case ACTION_CHECK_FOR_NEW_VISIBLE_TEXTURES:
+        // We set this false here and the caller must actively set this back
+        // to true for each frame that it still needs to check for uploads.
+        m_needsRedrawOnVisibleTextureUpload = false;
+        m_lastFrameNumberWhereRedrawOnVisibleTextureUploadAttempted = m_currentFrameNumber;
+        return;
+
     case ACTION_BEGIN_FRAME:
         DCHECK(!m_hasPendingTree);
         DCHECK(m_visible || m_needsForcedCommit);
@@ -277,6 +308,9 @@ bool SchedulerStateMachine::vsyncCallbackNeeded() const
     if (m_needsForcedRedraw)
         return true;
 
+    if (m_visible && m_needsRedrawOnVisibleTextureUpload)
+        return true;
+
     return m_needsRedraw && m_visible && m_outputSurfaceState == OUTPUT_SURFACE_ACTIVE;
 }
 
@@ -301,6 +335,11 @@ void SchedulerStateMachine::setNeedsRedraw()
     m_needsRedraw = true;
 }
 
+void SchedulerStateMachine::setNeedsRedrawOnVisibleTextureUpload()
+{
+    m_needsRedrawOnVisibleTextureUpload = true;
+}
+
 void SchedulerStateMachine::setNeedsForcedRedraw()
 {
     m_needsForcedRedraw = true;