Prevent display going to sleep while taking a screenshot

content/browser/renderer_host/render_widget_host_impl.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 "content/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 
 #include <set>
 #include <tuple>
@@ skipping 64 matching lines @@
 #include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/public/web/WebCompositionUnderline.h"
 #include "ui/events/event.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/geometry/vector2d_conversions.h"
 #include "ui/gfx/skbitmap_operations.h"
 #include "ui/snapshot/snapshot.h"
 
 #if defined(OS_MACOSX)
+#include "content/browser/power_save_blocker_impl.h"
+#include "content/public/browser/power_save_blocker_factory.h"
 #include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
 #endif
 
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
 using blink::WebGestureEvent;
 using blink::WebInputEvent;
 using blink::WebKeyboardEvent;
 using blink::WebMouseEvent;
@@ skipping 1170 matching lines @@
 
   // The resize message (which may not happen immediately) will carry with it
   // the screen info as well as the new size (if the screen has changed scale
   // factor).
   WasResized();
 }
 
 void RenderWidgetHostImpl::GetSnapshotFromBrowser(
     const GetSnapshotFromBrowserCallback& callback) {
   int id = next_browser_snapshot_id_++;
+
+#if defined(OS_MACOSX)
+  // MacOS version of underlying GrabViewSnapshot() blocks while
+  // display/GPU are in a power-saving mode, so make sure display
+  // does not go to sleep for the duration of reading a snapshot.
+  if (pending_browser_snapshots_.empty()) {
+    DCHECK(!power_save_blocker_);
+    power_save_blocker_.reset(static_cast<PowerSaveBlockerImpl*>(

[pfeldman, 2016/06/07 04:35:29]

Going impl for the sake of content/ policy seems artificial here. You could
leave it public, right?

+      CreatePowerSaveBlocker(
+          PowerSaveBlocker::kPowerSaveBlockPreventDisplaySleep,
+          PowerSaveBlocker::kReasonOther, "GetSnapshot")
+      .release()));
+  }
+#endif
   pending_browser_snapshots_.insert(std::make_pair(id, callback));
   Send(new ViewMsg_ForceRedraw(GetRoutingID(), id));
 }
 
 const NativeWebKeyboardEvent*
     RenderWidgetHostImpl::GetLastKeyboardEvent() const {
   return input_router_->GetLastKeyboardEvent();
 }
 
 void RenderWidgetHostImpl::OnSelectionChanged(const base::string16& text,
@@ skipping 832 matching lines @@
   // to be implicitly complete, and returned the same snapshot data.
   PendingSnapshotMap::iterator it = pending_browser_snapshots_.begin();
   while (it != pending_browser_snapshots_.end()) {
       if (it->first <= snapshot_id) {
         it->second.Run(data, size);
         pending_browser_snapshots_.erase(it++);
       } else {
         ++it;
       }
   }
+#if defined(OS_MACOSX)
+  if (pending_browser_snapshots_.empty())
+    power_save_blocker_.reset();
+#endif
 }
 
 void RenderWidgetHostImpl::OnSnapshotDataReceivedAsync(
     int snapshot_id,
     scoped_refptr<base::RefCountedBytes> png_data) {
   if (png_data.get())
     OnSnapshotDataReceived(snapshot_id, png_data->front(), png_data->size());
   else
     OnSnapshotDataReceived(snapshot_id, NULL, 0);
 }
@@ skipping 28 matching lines @@
   return delegate_ ? delegate_->GetRootBrowserAccessibilityManager() : NULL;
 }
 
 BrowserAccessibilityManager*
     RenderWidgetHostImpl::GetOrCreateRootBrowserAccessibilityManager() {
   return delegate_ ?
       delegate_->GetOrCreateRootBrowserAccessibilityManager() : NULL;
 }
 
 }  // namespace content