Track cc histograms using a global "client name" variable.

BUG=526192
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1321013004

Cr-Commit-Position: refs/heads/master@{#347565}
(cherry picked from commit 0d30216f14e3f5620de722412d76cbdb7759ec42)

TBR=chrishtr@chromium.org,wkorman@chromium.org

Review URL: https://codereview.chromium.org/1321913005 .

Cr-Commit-Position: refs/branch-heads/2490@{#189}
Cr-Branched-From: 7790a3535f2a81a03685eca31a32cf69ae0c114f-refs/heads/master@{#344925}

1 files changed, 13 insertions, 7 deletions

diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index a3a9b2c..7fe2181 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -23,6 +23,7 @@
 #include "cc/animation/scroll_offset_animation_curve.h"
 #include "cc/animation/scrollbar_animation_controller.h"
 #include "cc/animation/timing_function.h"
+#include "cc/base/histograms.h"
 #include "cc/base/math_util.h"
 #include "cc/debug/benchmark_instrumentation.h"
 #include "cc/debug/debug_rect_history.h"
@@ -1034,13 +1035,18 @@ DrawResult LayerTreeHostImpl::PrepareToDraw(FrameData* frame) {
       "Compositing.NumActiveLayers",
       base::saturated_cast<int>(active_tree_->NumLayers()), 1, 400, 20);
 
-  size_t total_picture_memory = 0;
-  for (const PictureLayerImpl* layer : active_tree()->picture_layers())
-    total_picture_memory += layer->GetRasterSource()->GetPictureMemoryUsage();
-  if (total_picture_memory != 0) {
-    UMA_HISTOGRAM_COUNTS(
-        "Compositing.PictureMemoryUsageKb",
-        base::saturated_cast<int>(total_picture_memory / 1024));
+  if (const char* client_name = GetClientNameForMetrics()) {
+    size_t total_picture_memory = 0;
+    for (const PictureLayerImpl* layer : active_tree()->picture_layers())
+      total_picture_memory += layer->GetRasterSource()->GetPictureMemoryUsage();
+    if (total_picture_memory != 0) {
+      // GetClientNameForMetrics only returns one non-null value over the
+      // lifetime of the process, so this histogram name is runtime constant.
+      UMA_HISTOGRAM_COUNTS(
+          base::StringPrintf("Compositing.%s.PictureMemoryUsageKb",
+                             client_name),
+          base::saturated_cast<int>(total_picture_memory / 1024));
+    }
   }
 
   bool update_lcd_text = false;