Ignores screenshot taking invocations if it's too close to the previous one.

chrome/browser/ui/ash/screenshot_taker.cc

Index: chrome/browser/ui/ash/screenshot_taker.cc
diff --git a/chrome/browser/ui/ash/screenshot_taker.cc b/chrome/browser/ui/ash/screenshot_taker.cc
index 3e9d6556604afb0d6749556cb4303679259d2b64..0e26839b441357591eede00aa1f91bf53999a7f0 100644
--- a/chrome/browser/ui/ash/screenshot_taker.cc
+++ b/chrome/browser/ui/ash/screenshot_taker.cc
@@ -33,6 +33,8 @@
 #endif
 
 namespace {
+const int kScreenshotMinimumIntervalInMS = 500;
+
 bool ShouldUse24HourClock() {
 #if defined(OS_CHROMEOS)
   Profile* profile = ProfileManager::GetDefaultProfileOrOffTheRecord();
@@ -142,6 +144,19 @@ void ScreenshotTaker::HandleTakePartialScreenshot(
     aura::Window* window, const gfx::Rect& rect) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 
+  aura::RootWindow* root_window = window->GetRootWindow();

[sky, 2012/07/20 16:13:31]

Do we really care about what root window this came from? Can't we have the time
apply to all?
If not, the map needs to be pruned when rootwindows are removed.

[Jun Mukai, 2012/07/20 17:07:32]

This method is invoked several times for a single Ctrl-F5 when multiple displays
are available.  see ash/accelerators/accelerator_controller.cc.  Possibly we can
check the timestamp in the accelerator_controller...

+  base::Time now = base::Time::Now();
+  std::map<aura::RootWindow*, base::Time>::const_iterator iter =
+      last_screenshot_timestamps_.find(root_window);
+  if (iter != last_screenshot_timestamps_.end()) {
+    base::Time last = iter->second;
+    // Ignore if the command is issued too closely to the last command.
+    if (now - last <= base::TimeDelta::FromMilliseconds(
+            kScreenshotMinimumIntervalInMS))
+      return;
+  }
+  last_screenshot_timestamps_[root_window] = now;
+
   scoped_refptr<base::RefCountedBytes> png_data(new base::RefCountedBytes);
 
   bool is_logged_in = true;