cc: Poll for state that triggers draws (synchronous compositor only)

cc/scheduler/scheduler.cc

 // Copyright 2011 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/scheduler/scheduler.h"
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "cc/debug/traced_value.h"
@@ skipping 133 matching lines @@
     has_pending_begin_frame_ = false;
     client_->SetNeedsBeginFrameOnImplThread(needs_begin_frame);
     last_set_needs_begin_frame_ = needs_begin_frame;
   }
 
   // Request another BeginFrame if we haven't drawn for now until we have
   // deadlines implemented.
   if (state_machine_.inside_begin_frame() && has_pending_begin_frame_) {
     has_pending_begin_frame_ = false;
     client_->SetNeedsBeginFrameOnImplThread(true);
-    return;
+  }
+
+  // Setup PollForAnticipatedDrawTriggers for cases where we want a proactive
+  // BeginFrame but aren't requesting one.
+  if (!needs_begin_frame &&
+      state_machine_.ProactiveBeginFrameWantedByImplThread()) {
+    if (poll_for_draw_triggers_closure_.IsCancelled()) {
+      poll_for_draw_triggers_closure_.Reset(
+          base::Bind(&Scheduler::PollForAnticipatedDrawTriggers,
+                     weak_factory_.GetWeakPtr()));
+      base::MessageLoop::current()->PostDelayedTask(
+          FROM_HERE,
+          poll_for_draw_triggers_closure_.callback(),
+          last_begin_frame_args_.interval);
+    }
+  } else {
+    poll_for_draw_triggers_closure_.Cancel();
   }
 }
 
 void Scheduler::BeginFrame(const BeginFrameArgs& args) {
   TRACE_EVENT0("cc", "Scheduler::BeginFrame");
   DCHECK(!has_pending_begin_frame_);
   has_pending_begin_frame_ = true;
   last_begin_frame_args_ = args;
   state_machine_.DidEnterBeginFrame(args);
   ProcessScheduledActions();
   state_machine_.DidLeaveBeginFrame();
 }
 
+void Scheduler::PollForAnticipatedDrawTriggers() {
+  TRACE_EVENT0("cc", "Scheduler::PollForAnticipatedDrawTriggers");
+  state_machine_.PollForAnticipatedDrawTriggers();
+  ProcessScheduledActions();
+}
+
 void Scheduler::DrawAndSwapIfPossible() {
   DrawSwapReadbackResult result =
       client_->ScheduledActionDrawAndSwapIfPossible();
   state_machine_.DidDrawIfPossibleCompleted(result.did_draw);
   if (result.did_swap)
     has_pending_begin_frame_ = false;
 }
 
 void Scheduler::DrawAndSwapForced() {
   DrawSwapReadbackResult result = client_->ScheduledActionDrawAndSwapForced();
@@ skipping 62 matching lines @@
 
   SetupNextBeginFrameIfNeeded();
   client_->DidAnticipatedDrawTimeChange(AnticipatedDrawTime());
 }
 
 bool Scheduler::WillDrawIfNeeded() const {
   return !state_machine_.PendingDrawsShouldBeAborted();
 }
 
 }  // namespace cc