Initialize device scale factor correctly on Android

ui/gfx/display.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/display.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/string_number_conversions.h"
 #include "base/stringprintf.h"
@@ skipping 65 matching lines @@
   return gfx::Insets(work_area_.y() - bounds_.y(),
                      work_area_.x() - bounds_.x(),
                      bounds_.bottom() - work_area_.bottom(),
                      bounds_.right() - work_area_.right());
 }
 
 void Display::SetScaleAndBounds(
     float device_scale_factor,
     const gfx::Rect& bounds_in_pixel) {
   Insets insets = bounds_.InsetsFrom(work_area_);
-  if (!HasForceDeviceScaleFactor())
+  if (!HasForceDeviceScaleFactor()) {
+#if defined(OS_CHROMEOS) || defined(OS_MACOSX)
+    // Unless an explicit scale factor was provided for testing, ensure the
+    // scale is integral.
+    device_scale_factor = static_cast<int>(device_scale_factor);
+#endif
     device_scale_factor_ = device_scale_factor;
+  }
+  device_scale_factor_ = std::max(1.0f, device_scale_factor_);

[oshima, 2012/11/14 16:52:35]

Is this necessary for android?
I most likely eliminate these safe guard in near future, and want to know if
I should do it only for chromeos, or can just eliminate for all platforms.

[johnme, 2012/11/14 16:56:45]

There should never be any harm in using this safeguard (as device_scale_factor_
should never be less than 1). So I'd recommend just keeping it for all
platforms.

 #if defined(USE_AURA)
   bounds_in_pixel_ = bounds_in_pixel;
 #endif
   bounds_ = gfx::Rect(gfx::ToFlooredSize(
       bounds_in_pixel.size().Scale(1.0f / device_scale_factor_)));
   UpdateWorkAreaFromInsets(insets);
 }
 
 void Display::SetSize(const gfx::Size& size_in_pixel) {
   SetScaleAndBounds(
@@ skipping 16 matching lines @@
 
 std::string Display::ToString() const {
   return base::StringPrintf("Display[%lld] bounds=%s, workarea=%s, scale=%f",
                             static_cast<long long int>(id_),
                             bounds_.ToString().c_str(),
                             work_area_.ToString().c_str(),
                             device_scale_factor_);
 }
 
 }  // namespace gfx