mac: Makeshift UI for scroll feedback.

chrome/browser/renderer_host/render_widget_host_view_mac.mm

Index: chrome/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/chrome/browser/renderer_host/render_widget_host_view_mac.mm b/chrome/browser/renderer_host/render_widget_host_view_mac.mm
index 682f0c9afede1232503e15064c666072b560966f..73e52d384fa09b589c65fa9153a3f2e71df946d9 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/chrome/browser/renderer_host/render_widget_host_view_mac.mm
@@ -25,6 +25,7 @@
 #include "chrome/browser/spellchecker/spellchecker_platform_engine.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
+#import "chrome/browser/ui/cocoa/history_overlay_controller.h"
 #import "chrome/browser/ui/cocoa/rwhvm_editcommand_helper.h"
 #import "chrome/browser/ui/cocoa/view_id_util.h"
 #include "chrome/common/render_messages.h"
@@ -1589,6 +1590,13 @@ void RenderWidgetHostViewMac::SetTextInputActive(bool active) {
         // rubberband or send back an event unhandled.
             (isPinnedLeft_ && !isRightScroll) ||
             (isPinnedRight_ && isRightScroll))) {
+
+      // Released by the tracking handler once the gesture is complete.
+      HistoryOverlayController* historyOverlay =
+          [[HistoryOverlayController alloc]
+            initForMode:goForward ? kHistoryOverlayModeForward :
+                                    kHistoryOverlayModeBack];
+
       // The way this api works: gestureAmount is between -1 and 1 (float). If
       // the user does the gesture for more than about 25% (i.e. < -0.25 or >
       // 0.25) and then lets go, it is accepted, we get a NSEventPhaseEnded,
@@ -1603,9 +1611,13 @@ void RenderWidgetHostViewMac::SetTextInputActive(bool active) {
                                              NSEventPhase phase,
                                              BOOL isComplete,
                                              BOOL *stop) {
+          if (phase == NSEventPhaseBegan) {
+            [historyOverlay showPanelForWindow:[self window]];
+            return;
+          }
+
           // |gestureAmount| obeys -[NSEvent isDirectionInvertedFromDevice]
           // automatically.
-          // TODO(thakis): UI.
           Browser* browser = BrowserList::GetLastActive();
           if (phase == NSEventPhaseEnded && browser) {
             if (goForward)
@@ -1613,6 +1625,12 @@ void RenderWidgetHostViewMac::SetTextInputActive(bool active) {
             else
               browser->GoBack(CURRENT_TAB);
           }
+
+          [historyOverlay setProgress:gestureAmount];
+          if (isComplete) {
+            [historyOverlay dismiss];
+            [historyOverlay release];
+          }
         }];
       return YES;
     }