Reduce CPU usage of download shelf UI. (both MD and pre-MD shelves)

chrome/browser/ui/views/download/download_item_view_md.cc

Index: chrome/browser/ui/views/download/download_item_view_md.cc
diff --git a/chrome/browser/ui/views/download/download_item_view_md.cc b/chrome/browser/ui/views/download/download_item_view_md.cc
index 1fbd1304bc0bf058f54d7b44eed775fc87507d40..5707d2729994c48f2b064afbb9573877677a548e 100644
--- a/chrome/browser/ui/views/download/download_item_view_md.cc
+++ b/chrome/browser/ui/views/download/download_item_view_md.cc
@@ -155,7 +155,7 @@ DownloadItemViewMd::DownloadItemViewMd(DownloadItem* download_item,
       model_(download_item),
       save_button_(nullptr),
       discard_button_(nullptr),
-      dropdown_button_(nullptr),
+      dropdown_button_(new BarControlButton(this)),
       dangerous_download_label_(nullptr),
       dangerous_download_label_sized_(false),
       disabled_while_opening_(false),
@@ -167,6 +167,8 @@ DownloadItemViewMd::DownloadItemViewMd(DownloadItem* download_item,
   download()->AddObserver(this);
   set_context_menu_controller(this);
 
+  AddChildView(dropdown_button_);
+
   LoadIcon();
 
   ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
@@ -182,8 +184,6 @@ DownloadItemViewMd::DownloadItemViewMd(DownloadItem* download_item,
 
   OnDownloadUpdated(download());
 
-  dropdown_button_ = new BarControlButton(this);
-  AddChildView(dropdown_button_);
   SetDropdownState(NORMAL);
   UpdateColorsFromTheme();
 }
@@ -205,10 +205,10 @@ void DownloadItemViewMd::StartDownloadProgress() {
   if (progress_timer_.IsRunning())
     return;
   progress_start_time_ = base::TimeTicks::Now();
-  progress_timer_.Start(
-      FROM_HERE,
-      base::TimeDelta::FromMilliseconds(DownloadShelf::kProgressRateMs),
-      base::Bind(&DownloadItemViewMd::SchedulePaint, base::Unretained(this)));
+  progress_timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(
+                                       DownloadShelf::kProgressRateMs),
+                        base::Bind(&DownloadItemViewMd::ProgressTimerFired,
+                                   base::Unretained(this)));
 }
 
 void DownloadItemViewMd::StopDownloadProgress() {
@@ -243,16 +243,9 @@ void DownloadItemViewMd::OnDownloadUpdated(DownloadItem* download_item) {
     return;
   }
 
-  if (IsShowingWarningDialog() && !model_.IsDangerous()) {
-    // We have been approved.
-    ClearWarningDialog();
-  } else if (!IsShowingWarningDialog() && model_.IsDangerous()) {
-    ShowWarningDialog();
-    // Force the shelf to layout again as our size has changed.
-    shelf_->Layout();
-    SchedulePaint();
+  if (IsShowingWarningDialog() != model_.IsDangerous()) {
+    ToggleWarningDialog();
   } else {
-    base::string16 status_text = model_.GetStatusText();
     switch (download()->GetState()) {
       case DownloadItem::IN_PROGRESS:
         download()->IsPaused() ? StopDownloadProgress()
@@ -265,7 +258,6 @@ void DownloadItemViewMd::OnDownloadUpdated(DownloadItem* download_item) {
         complete_animation_->SetSlideDuration(kInterruptedAnimationDurationMs);
         complete_animation_->SetTweenType(gfx::Tween::LINEAR);
         complete_animation_->Show();
-        SchedulePaint();
         LoadIcon();
         break;
       case DownloadItem::COMPLETE:
@@ -278,7 +270,6 @@ void DownloadItemViewMd::OnDownloadUpdated(DownloadItem* download_item) {
         complete_animation_->SetSlideDuration(kCompleteAnimationDurationMs);
         complete_animation_->SetTweenType(gfx::Tween::LINEAR);
         complete_animation_->Show();
-        SchedulePaint();
         LoadIcon();
         break;
       case DownloadItem::CANCELLED:
@@ -290,7 +281,8 @@ void DownloadItemViewMd::OnDownloadUpdated(DownloadItem* download_item) {
       default:
         NOTREACHED();
     }
-    status_text_ = status_text;
+    status_text_ = model_.GetStatusText();
+    SchedulePaint();
   }
 
   base::string16 new_tip = model_.GetTooltipText(font_list_, kTooltipMaxWidth);
@@ -300,11 +292,6 @@ void DownloadItemViewMd::OnDownloadUpdated(DownloadItem* download_item) {
   }
 
   UpdateAccessibleName();
-
-  // We use the parent's (DownloadShelfView's) SchedulePaint, since there
-  // are spaces between each DownloadItemViewMd that the parent is responsible
-  // for painting.
-  shelf_->SchedulePaint();
 }
 
 void DownloadItemViewMd::OnDownloadDestroyed(DownloadItem* download) {
@@ -491,7 +478,7 @@ void DownloadItemViewMd::ShowContextMenuForView(
 
 void DownloadItemViewMd::ButtonPressed(views::Button* sender,
                                        const ui::Event& event) {
-  if (dropdown_button_ && sender == dropdown_button_) {
+  if (sender == dropdown_button_) {
     // TODO(estade): this is copied from ToolbarActionView but should be shared
     // one way or another.
     ui::MenuSourceType type = ui::MENU_SOURCE_NONE;
@@ -832,6 +819,20 @@ void DownloadItemViewMd::SetDropdownState(State new_state) {
   SchedulePaint();
 }
 
+void DownloadItemViewMd::ToggleWarningDialog() {
+  if (model_.IsDangerous())
+    ShowWarningDialog();
+  else
+    ClearWarningDialog();
+
+  // We need to load the icon now that the download has the real path.
+  LoadIcon();
+
+  // Force the shelf to layout again as our size has changed.
+  shelf_->Layout();
+  shelf_->SchedulePaint();
+}
+
 void DownloadItemViewMd::ClearWarningDialog() {
   DCHECK(download()->GetDangerType() ==
          content::DOWNLOAD_DANGER_TYPE_USER_VALIDATED);
@@ -860,18 +861,10 @@ void DownloadItemViewMd::ClearWarningDialog() {
   dangerous_download_label_sized_ = false;
   cached_button_size_.SetSize(0, 0);
 
-  // Set the accessible name back to the status and filename instead of the
-  // download warning.
-  UpdateAccessibleName();
-
   // We need to load the icon now that the download has the real path.
   LoadIcon();
 
-  // Force the shelf to layout again as our size has changed.
-  shelf_->Layout();
-  shelf_->SchedulePaint();
-
-  TooltipTextChanged();
+  dropdown_button_->SetVisible(true);
 }
 
 void DownloadItemViewMd::ShowWarningDialog() {
@@ -918,7 +911,8 @@ void DownloadItemViewMd::ShowWarningDialog() {
   dangerous_download_label_->SetAutoColorReadabilityEnabled(false);
   AddChildView(dangerous_download_label_);
   SizeLabelToMinWidth();
-  TooltipTextChanged();
+
+  dropdown_button_->SetVisible(false);
 }
 
 gfx::ImageSkia DownloadItemViewMd::GetWarningIcon() {
@@ -1075,6 +1069,13 @@ void DownloadItemViewMd::AnimateStateTransition(
   }
 }
 
+void DownloadItemViewMd::ProgressTimerFired() {
+  // Only repaint for the indeterminate size case. Otherwise, we'll repaint only
+  // when there's an update notified via OnDownloadUpdated().
+  if (model_.PercentComplete() < 0)
+    SchedulePaint();
+}
+
 SkColor DownloadItemViewMd::GetTextColor() {
   return GetTextColorForThemeProvider(GetThemeProvider());
 }