Fix for the WebInputEventBuilderTest.TestMouseEventScale content_unittests failures on the DrMemory…

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 <algorithm>
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/geometry/point_f.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/switches.h"
 
 namespace gfx {
 namespace {
 
+// This variable tracks whether the forced device scale factor switch needs to
+// be read from the command line, i.e. if it is set to -1 then the command line
+// is checked.
+int g_has_forced_device_scale_factor = -1;
+
+// This variable caches the forced device scale factor value which is read off
+// the command line. If the cache is invalidated by setting this variable to
+// -1.0, we read the forced device scale factor again.
+float g_forced_device_scale_factor = -1.0;
+
 bool HasForceDeviceScaleFactorImpl() {
   return base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kForceDeviceScaleFactor);
 }
 
 float GetForcedDeviceScaleFactorImpl() {
   double scale_in_double = 1.0;
   if (HasForceDeviceScaleFactorImpl()) {
     std::string value =
         base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
             switches::kForceDeviceScaleFactor);
     if (!base::StringToDouble(value, &scale_in_double))
       LOG(ERROR) << "Failed to parse the default device scale factor:" << value;
   }
   return static_cast<float>(scale_in_double);
 }
 
 int64 internal_display_id_ = -1;
 
 }  // namespace
 
 const int64 Display::kInvalidDisplayID = -1;
 
 // static
 float Display::GetForcedDeviceScaleFactor() {
-  static const float kForcedDeviceScaleFactor =
-      GetForcedDeviceScaleFactorImpl();
-  return kForcedDeviceScaleFactor;
+  if (g_forced_device_scale_factor < 0)
+    g_forced_device_scale_factor = GetForcedDeviceScaleFactorImpl();
+  return g_forced_device_scale_factor;
 }
 
 //static
 bool Display::HasForceDeviceScaleFactor() {
-  static const bool kHasForceDeviceScaleFactor =
-      HasForceDeviceScaleFactorImpl();
-  return kHasForceDeviceScaleFactor;
+  if (g_has_forced_device_scale_factor == -1)
+    g_has_forced_device_scale_factor = HasForceDeviceScaleFactorImpl();
+  return !!g_has_forced_device_scale_factor;
+}
+
+// static
+void Display::ResetForceDeviceScaleFactorForTesting() {
+  g_has_forced_device_scale_factor = -1;
+  g_forced_device_scale_factor = -1.0;
 }
 
 Display::Display()
     : id_(kInvalidDisplayID),
       device_scale_factor_(GetForcedDeviceScaleFactor()),
       rotation_(ROTATE_0),
       touch_support_(TOUCH_SUPPORT_UNKNOWN) {
 }
 
 Display::Display(int64 id)
@@ skipping 117 matching lines @@
 
 int64 Display::InternalDisplayId() {
   return internal_display_id_;
 }
 
 void Display::SetInternalDisplayId(int64 internal_display_id) {
   internal_display_id_ = internal_display_id;
 }
 
 }  // namespace gfx