[Blimp Client] Avoids sending resize messages to engine with the same size info.

BUG=575297

Review URL: https://codereview.chromium.org/1569123002

Cr-Commit-Position: refs/heads/master@{#368394}

3 files changed, 46 insertions, 2 deletions

diff --git a/blimp/client/session/tab_control_feature.cc b/blimp/client/session/tab_control_feature.cc
index fc64b66..5b1ccd9 100644
--- a/blimp/client/session/tab_control_feature.cc
+++ b/blimp/client/session/tab_control_feature.cc
@@ -9,7 +9,6 @@
 #include "blimp/common/proto/size.pb.h"
 #include "blimp/common/proto/tab_control.pb.h"
 #include "blimp/net/blimp_message_processor.h"
-#include "ui/gfx/geometry/size.h"
 
 namespace blimp {
 
@@ -24,6 +23,13 @@ void TabControlFeature::set_outgoing_message_processor(
 
 void TabControlFeature::SetSizeAndScale(const gfx::Size& size,
                                         float device_pixel_ratio) {
+  if (last_size_ == size && last_device_pixel_ratio_ == device_pixel_ratio) {
+    return;
+  }
+
+  last_size_ = size;
+  last_device_pixel_ratio_ = device_pixel_ratio;
+
   SizeMessage* size_details;
   scoped_ptr<BlimpMessage> message = CreateBlimpMessage(&size_details);
   size_details->set_width(size.width());
diff --git a/blimp/client/session/tab_control_feature.h b/blimp/client/session/tab_control_feature.h
index ad62c6a..f439812 100644
--- a/blimp/client/session/tab_control_feature.h
+++ b/blimp/client/session/tab_control_feature.h
@@ -9,6 +9,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "blimp/client/blimp_client_export.h"
 #include "blimp/net/blimp_message_processor.h"
+#include "ui/gfx/geometry/size.h"
 
 namespace gfx {
 class Size;
@@ -41,6 +42,10 @@ class BLIMP_CLIENT_EXPORT TabControlFeature : public BlimpMessageProcessor {
   // Used to send BlimpMessage::TAB_CONTROL messages to the engine.
   scoped_ptr<BlimpMessageProcessor> outgoing_message_processor_;
 
+  // Used to avoid sending unnecessary messages to engine.
+  gfx::Size last_size_;
+  float last_device_pixel_ratio_ = -1;
+
   DISALLOW_COPY_AND_ASSIGN(TabControlFeature);
 };
 
diff --git a/blimp/client/session/tab_control_feature_unittest.cc b/blimp/client/session/tab_control_feature_unittest.cc
index c2969f5..8c60e2cc 100644
--- a/blimp/client/session/tab_control_feature_unittest.cc
+++ b/blimp/client/session/tab_control_feature_unittest.cc
@@ -51,7 +51,40 @@ TEST_F(TabControlFeatureTest, CreatesCorrectSizeMessage) {
       *out_processor_,
       MockableProcessMessage(EqualsSizeMessage(width, height, dp_to_px), _))
       .Times(1);
-  feature_.SetSizeAndScale(gfx::Size(width, height), 1.23f);
+  feature_.SetSizeAndScale(gfx::Size(width, height), dp_to_px);
+}
+
+TEST_F(TabControlFeatureTest, NoDuplicateSizeMessage) {
+  uint64_t width = 10;
+  uint64_t height = 15;
+  float dp_to_px = 1.23f;
+
+  EXPECT_CALL(
+      *out_processor_,
+      MockableProcessMessage(EqualsSizeMessage(width, height, dp_to_px), _))
+      .Times(1)
+      .RetiresOnSaturation();
+  EXPECT_CALL(
+      *out_processor_,
+      MockableProcessMessage(EqualsSizeMessage(width, height, dp_to_px + 1), _))
+      .Times(1)
+      .RetiresOnSaturation();
+  EXPECT_CALL(*out_processor_,
+              MockableProcessMessage(
+                  EqualsSizeMessage(width + 1, height, dp_to_px + 1), _))
+      .Times(1)
+      .RetiresOnSaturation();
+  EXPECT_CALL(*out_processor_,
+              MockableProcessMessage(
+                  EqualsSizeMessage(width + 1, height + 1, dp_to_px + 1), _))
+      .Times(1)
+      .RetiresOnSaturation();
+
+  feature_.SetSizeAndScale(gfx::Size(width, height), dp_to_px);
+  feature_.SetSizeAndScale(gfx::Size(width, height), dp_to_px);
+  feature_.SetSizeAndScale(gfx::Size(width, height), dp_to_px + 1);
+  feature_.SetSizeAndScale(gfx::Size(width + 1, height), dp_to_px + 1);
+  feature_.SetSizeAndScale(gfx::Size(width + 1, height + 1), dp_to_px + 1);
 }
 
 }  // namespace blimp