Fix Flash fullscreen focus regressions, and add interactive_ui_tests.

content/browser/web_contents/web_contents_view_mac.mm

Index: content/browser/web_contents/web_contents_view_mac.mm
diff --git a/content/browser/web_contents/web_contents_view_mac.mm b/content/browser/web_contents/web_contents_view_mac.mm
index 6e883b60db92581376da5041593be6a5edb5438b..9882c006b36ebb8e8921bbca3e4a1ae81719c5a5 100644
--- a/content/browser/web_contents/web_contents_view_mac.mm
+++ b/content/browser/web_contents/web_contents_view_mac.mm
@@ -158,9 +158,18 @@ void WebContentsViewMac::SizeContents(const gfx::Size& size) {
   // previous implementation.
 }
 
+gfx::NativeView WebContentsViewMac::GetNativeViewForFocus() const {
+  RenderWidgetHostView* rwhv =
+      web_contents_->GetFullscreenRenderWidgetHostView();
+  if (!rwhv)
+    rwhv = web_contents_->GetRenderWidgetHostView();
+  return rwhv ? rwhv->GetNativeView() : nil;
+}
+
 void WebContentsViewMac::Focus() {
-  NSWindow* window = [cocoa_view_.get() window];
-  [window makeFirstResponder:GetContentNativeView()];
+  const gfx::NativeView native_view = GetNativeViewForFocus();
+  NSWindow* const window = [native_view window];

[Avi (use Gerrit), 2014/10/24 23:04:05]

Why add |const| here?

[miu, 2014/10/25 00:04:32]

It's a declaration that the pointer will not be changed for the remainder of the
scope.  More details in other comment response...

+  [window makeFirstResponder:native_view];
   if (![window isVisible])
     return;
   [window makeKeyAndOrderFront:nil];
@@ -170,21 +179,23 @@ void WebContentsViewMac::SetInitialFocus() {
   if (web_contents_->FocusLocationBarByDefault())
     web_contents_->SetFocusToLocationBar(false);
   else
-    [[cocoa_view_.get() window] makeFirstResponder:GetContentNativeView()];
+    Focus();
 }
 
 void WebContentsViewMac::StoreFocus() {
+  const gfx::NativeView native_view = GetNativeViewForFocus();

[Avi (use Gerrit), 2014/10/24 23:04:05]

Again, why const here and below? It's very unusual to use const everywhere when
dealing with ObjC objects.

[miu, 2014/10/25 00:04:32]

Generally speaking, using const helps the compiler protect from unintended bugs
(e.g., logic that assumes a value does not change).  The Google C++ style guide
speaks to this:
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Use_of_const

Also, an interesting perspective on the topic:
http://gamesfromwithin.com/the-const-nazi

Note that in this code change it's the pointers that are const, not the objects
being pointed at.  Because they're all in methods with with few LOC, I'm okay
with removing them if they annoy you.  I'll admit I'm being very pedantic in
this particular code change, but it's [IMHO] a good habit that I've formed.

   // We're explicitly being asked to store focus, so don't worry if there's
   // already a view saved.
   focus_tracker_.reset(
-      [[FocusTracker alloc] initWithWindow:[cocoa_view_ window]]);
+      [[FocusTracker alloc] initWithWindow:[native_view window]]);
 }
 
 void WebContentsViewMac::RestoreFocus() {
+  const gfx::NativeView native_view = GetNativeViewForFocus();
   // TODO(avi): Could we be restoring a view that's no longer in the key view
   // chain?
   if (!(focus_tracker_.get() &&
-        [focus_tracker_ restoreFocusInWindow:[cocoa_view_ window]])) {
+        [focus_tracker_ restoreFocusInWindow:[native_view window]])) {
     // Fall back to the default focus behavior if we could not restore focus.
     // TODO(shess): If location-bar gets focus by default, this will
     // select-all in the field.  If there was a specific selection in