Minor cleanup for download item dragging.

* Make more things const.
* Remove |starting_drag_| member by making |drag_start_point_| an
  Optional.
* Reduce nesting by reordering conditionals.

Bug: none
Change-Id: I1910ddf86af8d1545095f7b9a7e3d5c7c8ad6653
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2255386Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780893}

chrome/browser/download/drag_download_item.h

@@ -19,7 +19,7 @@ class Image;
 // DownloadItem. If |icon| is NULL, no image will be accompany the drag. |view|
 // is only required for Mac OS X, elsewhere it can be NULL.
 void DragDownloadItem(const download::DownloadItem* download,
-                      gfx::Image* icon,
+                      const gfx::Image* icon,
                       gfx::NativeView view);
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DRAG_DOWNLOAD_ITEM_H_

chrome/browser/download/drag_download_item_aura.cc

@@ -29,7 +29,7 @@
 #endif
 
 void DragDownloadItem(const download::DownloadItem* download,
-                      gfx::Image* icon,
+                      const gfx::Image* icon,
                       gfx::NativeView view) {
   DCHECK(download);
   DCHECK_EQ(download::DownloadItem::COMPLETE, download->GetState());

chrome/browser/download/drag_download_item_mac.mm

@@ -35,7 +35,7 @@ id<NSDraggingSource> GetDraggingSource() {
 }
 
 void DragDownloadItem(const download::DownloadItem* download,
-                      gfx::Image* icon,
+                      const gfx::Image* icon,
                       gfx::NativeView native_view) {
   DCHECK_EQ(download::DownloadItem::COMPLETE, download->GetState());
   NSView* view = native_view.GetNativeNSView();

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

@@ -302,7 +302,6 @@ DownloadItemView::DownloadItemView(DownloadUIModel::DownloadUIModelPtr download,
       dropdown_state_(NORMAL),
       mode_(NORMAL_MODE),
       dragging_(false),
-      starting_drag_(false),
       model_(std::move(download)),
       save_button_(nullptr),
       discard_button_(nullptr),
@@ -444,31 +443,27 @@ void DownloadItemView::Layout() {
   }
 }
 
-// Handle drag (file copy) operations.
 bool DownloadItemView::OnMouseDragged(const ui::MouseEvent& event) {
+  // Handle drag (file copy) operations.
+
   // Mouse should not activate us in dangerous mode.
   if (IsShowingWarningDialog() || IsShowingMixedContentDialog())
     return true;
 
-  if (!starting_drag_) {
-    starting_drag_ = true;
+  if (!drag_start_point_)
     drag_start_point_ = event.location();
-  }
-  if (dragging_) {
-    if (model_->GetState() == DownloadItem::COMPLETE) {
-      IconManager* im = g_browser_process->icon_manager();
-      gfx::Image* icon = im->LookupIconFromFilepath(model_->GetTargetFilePath(),
-                                                    IconLoader::SMALL);
-      views::Widget* widget = GetWidget();
-      if (model_->download()) {
-        // TODO(shaktisahu): Make DragDownloadItem work with a model.
-        DragDownloadItem(model_->download(), icon,
-                         widget ? widget->GetNativeView() : nullptr);
-        RecordDownloadShelfDragEvent(DownloadShelfDragEvent::STARTED);
-      }
-    }
-  } else if (ExceededDragThreshold(event.location() - drag_start_point_)) {
-    dragging_ = true;
+  if (!dragging_) {
+    dragging_ = ExceededDragThreshold(event.location() - *drag_start_point_);
+  } else if ((model_->GetState() == DownloadItem::COMPLETE) &&
+             model_->download()) {
+    const gfx::Image* const file_icon =
+        g_browser_process->icon_manager()->LookupIconFromFilepath(
+            model_->GetTargetFilePath(), IconLoader::SMALL);
+    const views::Widget* const widget = GetWidget();
+    // TODO(shaktisahu): Make DragDownloadItem work with a model.
+    DragDownloadItem(model_->download(), file_icon,
+                     widget ? widget->GetNativeView() : nullptr);
+    RecordDownloadShelfDragEvent(DownloadShelfDragEvent::STARTED);
   }
   return true;
 }
@@ -481,7 +476,7 @@ void DownloadItemView::OnMouseCaptureLost() {
   if (dragging_) {
     // Starting a drag results in a MouseCaptureLost.
     dragging_ = false;
-    starting_drag_ = false;
+    drag_start_point_.reset();
   }
 }
 

chrome/browser/ui/views/download/download_item_view.h

@@ -22,6 +22,7 @@
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/optional.h"
 #include "base/strings/string_util.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/time/time.h"
@@ -318,11 +319,8 @@ class DownloadItemView : public views::View,
   // Whether we are dragging the download button.
   bool dragging_;
 
-  // Whether we are tracking a possible drag.
-  bool starting_drag_;
-
   // Position that a possible drag started at.
-  gfx::Point drag_start_point_;
+  base::Optional<gfx::Point> drag_start_point_;
 
   // For canceling an in progress icon request.
   base::CancelableTaskTracker cancelable_task_tracker_;