Add "panel_fitting" GPU feature type and use it for mirror mode.

content/browser/gpu/gpu_util.cc

Index: content/browser/gpu/gpu_util.cc
diff --git a/content/browser/gpu/gpu_util.cc b/content/browser/gpu/gpu_util.cc
index 267b2b4b78edbcc65e604852b999c32b15f91049..d4b86a0d1f17897f8df9ed7e5d13b17366e568dc 100644
--- a/content/browser/gpu/gpu_util.cc
+++ b/content/browser/gpu/gpu_util.cc
@@ -26,6 +26,7 @@ const char kGpuFeatureNameFlash3d[] = "flash_3d";
 const char kGpuFeatureNameFlashStage3d[] = "flash_stage3d";
 const char kGpuFeatureNameTextureSharing[] = "texture_sharing";
 const char kGpuFeatureNameAcceleratedVideoDecode[] = "accelerated_video_decode";
+const char kGpuFeatureNamePanelFitting[] = "panel_fitting";
 const char kGpuFeatureNameAll[] = "all";
 const char kGpuFeatureNameUnknown[] = "unknown";
 
@@ -101,6 +102,8 @@ GpuFeatureType StringToGpuFeatureType(const std::string& feature_string) {
     return content::GPU_FEATURE_TYPE_TEXTURE_SHARING;
   else if (feature_string == kGpuFeatureNameAcceleratedVideoDecode)
     return content::GPU_FEATURE_TYPE_ACCELERATED_VIDEO_DECODE;
+  else if (feature_string == kGpuFeatureNamePanelFitting)
+    return content::GPU_FEATURE_TYPE_PANEL_FITTING;
   else if (feature_string == kGpuFeatureNameAll)
     return content::GPU_FEATURE_TYPE_ALL;
   return content::GPU_FEATURE_TYPE_UNKNOWN;
@@ -127,6 +130,8 @@ std::string GpuFeatureTypeToString(GpuFeatureType type) {
       matches.push_back(kGpuFeatureNameTextureSharing);
     if (type & content::GPU_FEATURE_TYPE_ACCELERATED_VIDEO_DECODE)
       matches.push_back(kGpuFeatureNameAcceleratedVideoDecode);
+    if (type & content::GPU_FEATURE_TYPE_PANEL_FITTING)
+      matches.push_back(kGpuFeatureNamePanelFitting);
     if (!matches.size())
       matches.push_back(kGpuFeatureNameUnknown);
   }