Monitor the system native frame color on Win 10.

chrome/browser/themes/theme_service.cc

Index: chrome/browser/themes/theme_service.cc
diff --git a/chrome/browser/themes/theme_service.cc b/chrome/browser/themes/theme_service.cc
index 18f0a4f9630ac6396646bf44dd09837828dfe5cd..746d78cbb1829e51e8deb521e145a4bc8cfb2037 100644
--- a/chrome/browser/themes/theme_service.cc
+++ b/chrome/browser/themes/theme_service.cc
@@ -55,6 +55,8 @@
 #endif
 
 #if defined(OS_WIN)
+#include "base/win/windows_version.h"
+#include "skia/ext/skia_utils_win.h"
 #include "ui/base/win/shell.h"
 #endif
 
@@ -168,7 +170,19 @@ ThemeService::ThemeService()
       number_of_infobars_(0),
       original_theme_provider_(*this, false),
       incognito_theme_provider_(*this, true),
-      weak_ptr_factory_(this) {}
+      weak_ptr_factory_(this) {
+#if defined(OS_WIN)
+  // This just checks for Windows 10 instead of calling ShouldUseDwmFrameColor()
+  // because we want to monitor the frame color even when a custom frame is in
+  // use, so that it will be correct if at any time the user switches to the
+  // native frame.
+  if (base::win::GetVersion() >= base::win::VERSION_WIN10) {
+    dwm_key_.reset(new base::win::RegKey(
+        HKEY_CURRENT_USER, L"SOFTWARE\\Microsoft\\Windows\\DWM", KEY_READ));

[Bret, 2016/02/29 18:29:03]

Are you sure this is actually the frame color? When I messed around with this
earlier Windows would only report to me the base accent color (i.e. the color
you get when you pick the swatch from the settings page), not the actual color
it uses to draw an active frame. They're slightly different.

If you're not using this to actually draw the active frame this is probably
fine, but don't call it "frame color" because that's not quite correct.

[Peter Kasting, 2016/02/29 19:57:06]

On my system, the swatch color and the frame color are exactly the same for all
the swatches I tried (~9) and the color in the registry matched those for the
cases I looked at (~4).

If there's a particular problematic swatch on your system, let me know so I can
test it on mine.

+    OnDwmKeyUpdated();
+  }
+#endif
+}
 
 ThemeService::~ThemeService() {
   FreePlatformCaches();
@@ -475,6 +489,20 @@ SkColor ThemeService::GetColor(int id, bool incognito) const {
   const int kLabelBackground =
       ThemeProperties::COLOR_SUPERVISED_USER_LABEL_BACKGROUND;
   switch (id) {
+#if defined(OS_WIN)
+    case ThemeProperties::COLOR_FRAME:
+    case ThemeProperties::COLOR_FRAME_INCOGNITO:
+      // Active native windows on Windows 10 may have a custom frame color.
+      if (ShouldUseDwmFrameColor())
+        return dwm_frame_color_;
+      break;
+    case ThemeProperties::COLOR_FRAME_INACTIVE:
+    case ThemeProperties::COLOR_FRAME_INCOGNITO_INACTIVE:
+      // Inactive native windows on Windows 10 always have a white frame.
+      if (ShouldUseDwmFrameColor())
+        return SK_ColorWHITE;
+      break;
+#endif
     case ThemeProperties::COLOR_TOOLBAR_BUTTON_ICON:
       return color_utils::HSLShift(
           gfx::kChromeIconGrey,
@@ -738,6 +766,30 @@ void ThemeService::SetSupervisedUserTheme() {
 }
 #endif
 
+#if defined(OS_WIN)
+bool ThemeService::ShouldUseDwmFrameColor() const {
+  return ShouldUseNativeFrame() &&
+         (base::win::GetVersion() >= base::win::VERSION_WIN10);
+}
+
+void ThemeService::OnDwmKeyUpdated() {
+  // Attempt to read the accent color.
+  DWORD accent_color, color_prevalence;
+  dwm_frame_color_ =
+      ((dwm_key_->ReadValueDW(L"ColorPrevalence", &color_prevalence) ==
+        ERROR_SUCCESS) &&
+       (color_prevalence == 1) &&
+       (dwm_key_->ReadValueDW(L"AccentColor", &accent_color) == ERROR_SUCCESS))
+          ? skia::COLORREFToSkColor(accent_color)
+          : SK_ColorWHITE;
+
+  // Watch for future changes.
+  if (!dwm_key_->StartWatching(
+          base::Bind(&ThemeService::OnDwmKeyUpdated, base::Unretained(this))))
+    dwm_key_.reset();
+}
+#endif
+
 void ThemeService::OnInfobarDisplayed() {
   number_of_infobars_++;
 }