Fix partial-screen flashes when first entering low power full screen.

chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.mm

 // Copyright 2016 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 "chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.h"
 
 #include "ui/base/cocoa/animation_utils.h"
 #include "ui/gfx/mac/scoped_cocoa_disable_screen_updates.h"
 
 namespace {
 
 // The number of frames we need to be in the WarmUp state before moving to the
 // Enabled state.
 const uint64_t kWarmUpFramesBeforeEnteringLowPowerMode = 30;
 
 }  // namespace
 
 @interface FullscreenLowPowerWindow : NSWindow {
   base::scoped_nsobject<NSWindow> eventTargetWindow_;
 }
 - (id)initWithEventTargetWindow:(NSWindow*)eventTargetWindow
                       withLayer:(CALayer*)layer;
 @end
 
 @implementation FullscreenLowPowerWindow
 - (id)initWithEventTargetWindow:(NSWindow*)eventTargetWindow
                       withLayer:(CALayer*)layer {
+  // Resizing an NSWindow can be slow, so try to guess the right size at
+  // creation.
+  NSRect screenFrame = [[eventTargetWindow screen] frame];
+  NSRect initialRect = NSMakeRect(
+      0, 0, NSWidth(screenFrame), NSHeight(screenFrame));
   if (self = [super
-          initWithContentRect:NSMakeRect(0, 0, 256, 256)
+          initWithContentRect:initialRect
                     styleMask:NSTitledWindowMask | NSResizableWindowMask |
                               NSFullSizeContentViewWindowMask
                       backing:NSBackingStoreBuffered
                         defer:NO]) {
     eventTargetWindow_.reset(eventTargetWindow, base::scoped_policy::RETAIN);
     [self setCollectionBehavior:NSWindowCollectionBehaviorIgnoresCycle];
     [self setExcludedFromWindowsMenu:YES];
     [self setReleasedWhenClosed:NO];
     [self setIgnoresMouseEvents:YES];
 
@@ skipping 138 matching lines @@
       widget_ && low_power_window_ && low_power_layer_valid_ &&
       allowed_by_fullscreen_transition_ && allowed_by_nsview_layout_ &&
       allowed_by_child_windows_ && allowed_by_active_sheet_;
 
   switch (state_) {
     case Disabled:
       if (can_use_low_power_window) {
         // Ensure that the window's frame and style are set, and order it behind
         // the main window, so that it's ready to be moved in front.
         state_ = WarmingUp;
+
+        // Changing the size of the Window will also change the size of the
+        // views/layers. Disable implicit animations.
+        ScopedCAActionDisabler disabler;
         [low_power_window_ setStyleMask:[low_power_window_ styleMask] |
                                         NSFullScreenWindowMask];
         [low_power_window_ setFrame:[content_window_ frame]
                             display:YES
                             animate:NO];
         [low_power_window_ orderWindow:NSWindowBelow
                             relativeTo:[content_window_ windowNumber]];
       }
       break;
     case WarmingUp:
@@ skipping 18 matching lines @@
         }
       } else {
         // Move behind the main window.
         state_ = Disabled;
         [low_power_window_ orderWindow:NSWindowBelow
                             relativeTo:[content_window_ windowNumber]];
       }
       break;
   }
 }