Make some updates to BM bar for MD.

chrome/browser/ui/views/bookmarks/bookmark_bar_instructions_view.cc

Index: chrome/browser/ui/views/bookmarks/bookmark_bar_instructions_view.cc
diff --git a/chrome/browser/ui/views/bookmarks/bookmark_bar_instructions_view.cc b/chrome/browser/ui/views/bookmarks/bookmark_bar_instructions_view.cc
index 7c5787ba8f851eb515c1e5429bb98fd9bc9a8274..6a88dbd9d0024b8ca5724373ce86ba3f45648896 100644
--- a/chrome/browser/ui/views/bookmarks/bookmark_bar_instructions_view.cc
+++ b/chrome/browser/ui/views/bookmarks/bookmark_bar_instructions_view.cc
@@ -13,7 +13,9 @@
 #include "chrome/grit/generated_resources.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/base/l10n/l10n_util.h"
+#include "ui/base/resource/material_design/material_design_controller.h"
 #include "ui/base/theme_provider.h"
+#include "ui/native_theme/native_theme.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/controls/link.h"
 
@@ -31,8 +33,11 @@ BookmarkBarInstructionsView::BookmarkBarInstructionsView(
       import_link_(NULL),
       baseline_(-1),
       updated_colors_(false) {
-  instructions_ = new views::Label(
-      l10n_util::GetStringUTF16(IDS_BOOKMARKS_NO_ITEMS));
+  base::string16 instructions_text =
+      l10n_util::GetStringUTF16(IDS_BOOKMARKS_NO_ITEMS);
+  if (ui::MaterialDesignController::IsModeMaterial())
+    instructions_text += base::ASCIIToUTF16(" ");

[sky, 2015/10/19 15:38:40]

Why do you add a space for material? Might the space have undesirable effects in
other languages?

[Evan Stade, 2015/10/19 16:49:52]

Previously this space was implemented with kViewPadding, but that didn't create
the right amount of space (especially if you change the font). I tried to think
of how this could fail in other languages. It works in RTL and LTR. In languages
without space characters it creates too much space (I just tested with zh_CN),
but that was already a problem. Also it doesn't look that bad because the zh_CN
period character [。] already has some trailing empty space attached, so we get a
slightly too-wide space rather than a space where there should be none.

[jungshik at Google, 2015/10/23 06:30:19]

Sorry for the late reply and thanks for testing in various locales. 
Even though there's no side effect, I really wish we could do without adding an
extra space, but apparently not. 

BTW, "。" (Ideographic full stop) is so-called 'full-width' and its advance width
is the same as other CJK Ideographs. 

+  instructions_ = new views::Label(instructions_text);
   instructions_->SetAutoColorReadabilityEnabled(false);
   AddChildView(instructions_);
 
@@ -62,7 +67,8 @@ gfx::Size BookmarkBarInstructionsView::GetPreferredSize() const {
     }
     width += pref.width();
   }
-  width += (child_count() - 1) * kViewPadding;
+  if (!ui::MaterialDesignController::IsModeMaterial())
+    width += (child_count() - 1) * kViewPadding;
   if (ascent != 0)
     height = std::max(ascent + descent, height);
   return gfx::Size(width, height);
@@ -82,7 +88,9 @@ void BookmarkBarInstructionsView::Layout() {
       y = (height() - pref.height()) / 2;
     int view_width = std::min(remaining_width, pref.width());
     view->SetBounds(x, y, view_width, pref.height());
-    x += view_width + kViewPadding;
+    x += view_width;
+    if (!ui::MaterialDesignController::IsModeMaterial())
+      x += kViewPadding;
     remaining_width = std::max(0, width() - x);
   }
 }
@@ -128,6 +136,26 @@ void BookmarkBarInstructionsView::UpdateColors() {
   SkColor text_color =
       theme_provider->GetColor(ThemeProperties::COLOR_BOOKMARK_TEXT);
   instructions_->SetEnabledColor(text_color);
-  if (import_link_)
-    import_link_->SetEnabledColor(text_color);
+  if (import_link_) {

[varkha, 2015/10/19 15:01:29]

nit: could return early on !import_link to simplify the rest.

[Evan Stade, 2015/10/19 16:49:52]

Done.

+    if (!ui::MaterialDesignController::IsModeMaterial()) {
+      import_link_->SetEnabledColor(text_color);
+    } else {
+      // For MD, use the default link color if it provides enough contrast. If
+      // contrast is too low, fall back to the bookmark text color and use an
+      // underline to make it obvious it's a link. The default color readability
+      // code (which only adjusts luminance) doesn't work well in this case.
+      SkColor bg = theme_provider->GetColor(
+          ThemeProperties::ThemeProperties::COLOR_TOOLBAR);
+      SkColor link_color = GetNativeTheme()->GetSystemColor(
+          ui::NativeTheme::kColorId_LinkEnabled);
+      if (color_utils::GetContrastRatio(link_color, bg) >=
+          color_utils::kMinimumReadableContrastRatio) {
+        import_link_->SetUnderline(false);
+        import_link_->SetEnabledColor(link_color);
+      } else {
+        import_link_->SetUnderline(true);
+        import_link_->SetEnabledColor(text_color);
+      }

[varkha, 2015/10/19 15:01:29]

nit: maybe shorten this similar to:

bool enough_contrast = color_utils::GetContrastRatio(link_color, bg) >=
color_utils::kMinimumReadableContrastRatio;
import_link_->SetUnderline(!enough_contrast);
import_link_->SetEnabledColor(enough_contrast ? link_color : text_color);

[Evan Stade, 2015/10/19 16:49:52]

Done.

+    }
+  }
 }