Suppress a valgrind uninitialilzed read.

tools/valgrind/memcheck/suppressions.txt

 # There are four kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 5867 matching lines @@
    fun:_ZN5views6WidgetD0Ev
    fun:_ZN10scoped_ptrIN5views6WidgetEED1Ev
    fun:_ZN17StatusBubbleViewsD0Ev
    fun:_ZN10scoped_ptrI17StatusBubbleViewsED1Ev
    fun:_ZN11BrowserViewD0Ev
    fun:_ZN5views4ViewD2Ev
    fun:_ZN5views13NonClientViewD0Ev
    fun:_ZN10scoped_ptrIN5views4ViewEED1Ev
    fun:_ZN5views4View17DoRemoveChildViewEPS0_bbb
 }
+{
+   116475
+   Memcheck:Uninitialized
+   fun:_ZNK4base9Histogram11BucketIndexEi
+   fun:_ZN4base9Histogram3AddEi
+   fun:_ZN11webkit_glue25WebKitPlatformSupportImpl21histogramCustomCountsEPKciiii
+   fun:_ZN7WebCore15PlatformSupport21histogramCustomCountsEPKciiii
+   fun:_ZN7WebCore19CCLayerTreeHostImpl20optimizeRenderPassesERN3WTF6VectorINS1_6OwnPtrINS_12CCRenderPassEEELj0EEE
+   fun:_ZN7WebCore19CCLayerTreeHostImpl10drawLayersEv
+   fun:_ZN7WebCore19CCSingleThreadProxy11doCompositeEv
+   fun:_ZN7WebCore19CCSingleThreadProxy20compositeImmediatelyEv
+   fun:_ZN7WebCore15CCLayerTreeHost9compositeEv
+   fun:_ZN6WebKit16WebLayerTreeView9compositeEv
+}
+
 
 #-----------------------------------------------------------------------
 # 4. These only occur on our Google workstations
 
 {
    bug_todo_getdelim
    Memcheck:Leak
    fun:malloc
    fun:getdelim
    ...
    fun:call_init
    fun:_dl_init
 }
 {
    bug_todo_getdelim2
    Memcheck:Leak
    fun:malloc
    fun:getdelim
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
 }
 {
    bug_todo_grep
    Memcheck:Leak
    fun:malloc
    obj:/bin/grep
    obj:/bin/grep
 }