Mac fullscreen low power: Add unittests

chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.mm

Index: chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.mm
diff --git a/chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.mm b/chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.mm
index 17c64d1cf6841f2ad56eca335ba37444f700dd3c..a7e9e812bea62a7ff4faa8a960d5c4ae8b737610 100644
--- a/chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.mm
+++ b/chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.mm
@@ -4,9 +4,6 @@
 
 #include "chrome/browser/ui/cocoa/fullscreen_low_power_coordinator.h"
 
-#include "base/command_line.h"
-#include "chrome/common/chrome_switches.h"
-
 @interface FullscreenLowPowerWindow : NSWindow {
   base::scoped_nsobject<NSWindow> eventTargetWindow_;
 }
@@ -127,12 +124,17 @@ - (void)sendEvent:(NSEvent*)event {
 
     // Don't make any assumptions about other child windows.
     allowed_by_child_windows_ = false;
-    return;
+    break;
   }
+
+  EnterOrExitLowPowerModeIfNeeded();

[ccameron, 2016/06/08 03:47:18]

Oops -- I didn't notice this bug until I wrote a test for it.

 }
 
 void FullscreenLowPowerCoordinatorCocoa::SetLowPowerLayerValid(bool valid) {
-  low_power_layer_valid_ = valid;
+  if (valid)
+    low_power_layer_valid_frame_count_ += 1;
+  else
+    low_power_layer_valid_frame_count_ = 0;
   EnterOrExitLowPowerModeIfNeeded();
 }
 
@@ -144,15 +146,13 @@ - (void)sendEvent:(NSEvent*)event {
 }
 
 void FullscreenLowPowerCoordinatorCocoa::EnterOrExitLowPowerModeIfNeeded() {
-  static bool enabled_at_command_line =
-      base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableFullscreenLowPowerMode);
+  const uint64_t kMinValidFrames = 15;

[spqchan, 2016/06/08 21:43:58]

Put this as a constant at the top of the file.

[ccameron, 2016/06/09 20:47:08]

Done.

 
   bool new_in_low_power_mode =
-      widget_ && low_power_window_ && low_power_layer_valid_ &&
-      allowed_by_fullscreen_transition_ &&
-      allowed_by_nsview_layout_ && allowed_by_child_windows_ &&
-      allowed_by_active_sheet_ && enabled_at_command_line;
+      widget_ && low_power_window_ &&
+      low_power_layer_valid_frame_count_ > kMinValidFrames &&
+      allowed_by_fullscreen_transition_ && allowed_by_nsview_layout_ &&
+      allowed_by_child_windows_ && allowed_by_active_sheet_;
 
   if (new_in_low_power_mode) {
     // Update whether or not we are in low power mode based on whether or not