ChromeOS MD: Fix cannot drag tab onto immersive fullscreen window

chrome/browser/ui/views/frame/browser_view.cc

Index: chrome/browser/ui/views/frame/browser_view.cc
diff --git a/chrome/browser/ui/views/frame/browser_view.cc b/chrome/browser/ui/views/frame/browser_view.cc
index 3b3b4dd7247e0a1d84ea71220ab841c8490a4688..e10a574acde311e29154faf89fa259237cabd51c 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -152,6 +152,7 @@
 #endif
 
 #if defined(USE_ASH)
+#include "ash/common/material_design/material_design_controller.h"
 #include "chrome/browser/ui/ash/ash_util.h"
 #endif
 
@@ -526,9 +527,15 @@ gfx::Point BrowserView::OffsetPointForToolbarBackgroundImage(
 }
 
 bool BrowserView::IsTabStripVisible() const {
-  if (immersive_mode_controller_->ShouldHideTopViews() &&
-      immersive_mode_controller_->ShouldHideTabIndicators()) {
-    return false;
+  if (immersive_mode_controller_->ShouldHideTopViews()) {
+#if defined(USE_ASH)

[sky, 2017/02/01 16:31:37]

USE_ASH is now the same as OS_CHROMEOS and will eventually be replaced by it.
Please use OS_CHROMEOS in new code (as your touching includes above, please
merge the USE_ASH and OS_CHROMEOS sections.

[Qiang(Joe) Xu, 2017/02/01 18:58:09]

Done.

+    // For MD immersive fullscreen, tabstrip is considered as visible. Since top
+    // container is off screen, tapstrip is still invisible to user.
+    if (ash::MaterialDesignController::IsImmersiveModeMaterial())

[sky, 2017/02/01 16:31:37]

Does it really matter whether md or not? I'm wondering if we can remove the
branch (lines 530-539) entirely?

[Qiang(Joe) Xu, 2017/02/01 18:58:10]

done, and I find IsImmersiveModeMaterial is equivalent to
ShouldHideTabIndicators. So we can completely remote this trunk of lines.

+      return true;
+#endif
+    if (immersive_mode_controller_->ShouldHideTabIndicators())
+      return false;
   }
 
   // Return false if this window does not normally display a tabstrip.