Implementation of dwrite font proxy and removal of dwrite font cache

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 731b5b6eeff69147103aa0315ed844e14fab39fe..4572f6d3361578c5f1b0a90d01f7b2f0777c1cb0 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -8919,6 +8919,18 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="DWriteFontProxy.LoaderType" enum="DWriteFontLoaderType">

[Alexei Svitkine (slow), 2015/11/03 19:06:46]

There's already a DirectWrite.Fonts. prefix, so please re-use that one rather
than introducing a new one.

[Ilya Kulshin, 2015/11/04 19:04:02]

Done.

+  <owner>kulshin@chromium.org</owner>
+  <summary>The codepath that was used to load a font family.</summary>

[Alexei Svitkine (slow), 2015/11/03 19:06:46]

Is this logged for every font load? Mention this in the description. Same below.

[Ilya Kulshin, 2015/11/04 19:04:02]

Done.

+</histogram>
+
+<histogram name="DWriteFontProxy.LoadFamily" enum="DWriteLoadFamilyResult">
+  <owner>kulshin@chromium.org</owner>
+  <summary>
+    The outcome of attempting to load a font family in the renderer.
+  </summary>
+</histogram>
+
 <histogram name="EasyUnlock.AuthenticationSuccess" enum="BooleanSuccess">
   <owner>joshwoodward@google.com</owner>
   <owner>isherman@chromium.org</owner>
@@ -56761,6 +56773,21 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="2" label="Unknown"/>
 </enum>
 
+<enum name="DWriteFontLoaderType" type="int">
+  <int value="0" label="File: system font directory"/>
+  <int value="1" label="File: sandbox whitelisted"/>
+  <int value="2" label="File: outside sandbox whitelist"/>
+  <int value="3" label="Other"/>
+</enum>
+
+<enum name="DWriteLoadFamilyResult" type="int">
+  <int value="0" label="Success: single family"/>
+  <int value="1" label="Success: matched from collection"/>
+  <int value="2" label="Error: multiple families"/>
+  <int value="3" label="Error: no families"/>
+  <int value="4" label="Error: failed to create colleciton"/>
+</enum>
+
 <enum name="EAPInnerProtocol" type="int">
   <int value="0" label="UNKNOWN"/>
   <int value="1" label="NONE"/>